feat: merge Composer paste handling from develop

Cargo.lock

@@ -4402,10 +4402,12 @@ dependencies = [
  "agen",
  "async-trait",
  "base64 0.22.1",
+ "fs4",
  "futures",
  "protocol",
  "serde",
  "serde_json",
+ "sha2 0.11.0",
  "tempfile",
  "thiserror 2.0.18",
  "tokio",

crates/protocol/src/lib.rs

@@ -193,6 +193,64 @@ impl WorkerEvent {
 /// variants — emits an alert and inserts a `[unknown input segment]`
 /// placeholder into the LLM context so neither user nor LLM is blind to
 /// the dropped intent.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
+#[serde(rename_all = "snake_case")]
+pub enum PasteArtifactMediaType {
+    TextPlainUtf8,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
+#[serde(rename_all = "snake_case")]
+pub enum PasteArtifactAvailability {
+    Available,
+    Unavailable,
+    IntegrityFailed,
+}
+
+impl PasteArtifactMediaType {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::TextPlainUtf8 => "text/plain; charset=utf-8",
+        }
+    }
+}
+
+impl PasteArtifactAvailability {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::Available => "available",
+            Self::Unavailable => "unavailable",
+            Self::IntegrityFailed => "integrity_failed",
+        }
+    }
+}
+
+/// Session-owned reference to a large pasted-input artifact.
+///
+/// The reference contains only bounded integrity and provenance metadata. The
+/// artifact body remains in session storage and is available to the model only
+/// through the scoped paste-artifact tools installed by Worker.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
+pub struct PasteArtifactRef {
+    pub artifact_id: String,
+    pub created_at_ms: u64,
+    pub media_type: PasteArtifactMediaType,
+    /// Availability observed when this immutable reference was committed.
+    /// Reads revalidate storage and integrity rather than trusting this field.
+    pub availability: PasteArtifactAvailability,
+    pub byte_len: u64,
+    pub char_count: u64,
+    pub line_count: u64,
+    pub sha256: String,
+    pub source_entry_id: String,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
 #[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
@@ -210,6 +268,10 @@ pub enum Segment {
         lines: u32,
         content: String,
     },
+    /// Internal reference produced when Worker stores a large `Paste` before
+    /// committing input. Clients may receive this in history/event projections;
+    /// the body is intentionally absent.
+    PasteArtifact { artifact: PasteArtifactRef },
     /// `@<path>` file-system reference. Worker resolves readable files to
     /// `[File: <path>]` attachments and readable normal directories to shallow
     /// `[Dir: <path>]` listings; the flattened user text keeps the literal
@@ -250,6 +312,21 @@ impl Segment {
             match seg {
                 Segment::Text { content } => out.push_str(content),
                 Segment::Paste { content, .. } => out.push_str(content),
+                Segment::PasteArtifact { artifact } => {
+                    use std::fmt::Write as _;
+                    let _ = write!(
+                        out,
+                        "[Large paste stored as artifact {}: {} bytes, {} chars, {} lines, {}, {}, created at {} ms, sha256 {}; use SearchInputArtifact and ReadInputArtifact to inspect it]",
+                        artifact.artifact_id,
+                        artifact.byte_len,
+                        artifact.char_count,
+                        artifact.line_count,
+                        artifact.media_type.as_str(),
+                        artifact.availability.as_str(),
+                        artifact.created_at_ms,
+                        artifact.sha256
+                    );
+                }
                 Segment::FileRef { path } => {
                     out.push('@');
                     out.push_str(path);
@@ -1202,6 +1279,32 @@ mod tests {
         }
     }
 
+    #[test]
+    fn paste_artifact_segment_roundtrips_without_body() {
+        let artifact = PasteArtifactRef {
+            artifact_id: "019ca7c8-57b6-7f05-8edf-524147aba7b2".to_string(),
+            created_at_ms: 1_700_000_000_000,
+            media_type: PasteArtifactMediaType::TextPlainUtf8,
+            availability: PasteArtifactAvailability::Available,
+            byte_len: 65_536,
+            char_count: 65_530,
+            line_count: 200,
+            sha256: "a".repeat(64),
+            source_entry_id: "entry-1".to_string(),
+        };
+        let segment = Segment::PasteArtifact {
+            artifact: artifact.clone(),
+        };
+        let json = serde_json::to_string(&segment).unwrap();
+        assert!(!json.contains("pasted body"));
+        assert_eq!(serde_json::from_str::<Segment>(&json).unwrap(), segment);
+        let projected = Segment::flatten_to_text(&[segment]);
+        assert!(projected.contains(&artifact.artifact_id));
+        assert!(projected.contains("SearchInputArtifact"));
+        assert!(projected.contains("ReadInputArtifact"));
+        assert!(!projected.contains("pasted body"));
+    }
+
     #[test]
     fn method_run_flow_segment_roundtrip() {
         let method = Method::Run {

crates/protocol/src/typescript.rs

@@ -7,8 +7,9 @@ use crate::{
     CommandStreamSlice, CompactionLifecycle, CompactionLifecycleState, CompletionEntry,
     CompletionKind, ErrorCode, Event, Greeting, InFlightBlock, InFlightSnapshot,
     InFlightToolCallState, InternalWorkerKind, InternalWorkerRef, InternalWorkerSnapshot,
-    InvokeKind, MemoryWorkerEvent, Method, Permission, RewindSummary, RewindTarget, RewindTargetId,
-    RunResult, ScopeRule, Segment, SessionContentPart, SessionEntryProvenance, SessionMessageRole,
+    InvokeKind, MemoryWorkerEvent, Method, PasteArtifactAvailability, PasteArtifactMediaType,
+    PasteArtifactRef, Permission, RewindSummary, RewindTarget, RewindTargetId, RunResult,
+    ScopeRule, Segment, SessionContentPart, SessionEntryProvenance, SessionMessageRole,
     SessionSnapshot, SessionSnapshotEntry, SessionSnapshotEntryData, SessionToolAttachment,
     ToolResultDisposition, TurnResult, WorkerEvent, WorkerStatus,
     subscription::{
@@ -78,6 +79,9 @@ pub fn generated_protocol_types() -> String {
     push_decl::<Greeting>(&cfg, &mut output);
     push_decl::<Alert>(&cfg, &mut output);
     push_decl::<MemoryWorkerEvent>(&cfg, &mut output);
+    push_decl::<PasteArtifactMediaType>(&cfg, &mut output);
+    push_decl::<PasteArtifactAvailability>(&cfg, &mut output);
+    push_decl::<PasteArtifactRef>(&cfg, &mut output);
     push_decl::<Segment>(&cfg, &mut output);
     push_decl::<WorkerEvent>(&cfg, &mut output);
     push_decl::<SubscriptionRequestId>(&cfg, &mut output);

crates/session-store/Cargo.toml

@@ -8,8 +8,10 @@ license.workspace = true
 [dependencies]
 base64.workspace = true
 agen = { workspace = true }
+fs4.workspace = true
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
+sha2.workspace = true
 uuid = { workspace = true, features = ["v7", "serde"] }
 thiserror = { workspace = true }
 protocol = { workspace = true }

crates/session-store/src/fs_store.rs

@@ -16,9 +16,11 @@
 //! enumerable by the picker.
 
 use crate::event_trace::TraceEntry;
+use crate::paste_artifact::{read_from_dir, write_to_dir};
 use crate::segment_log::LogEntry;
 use crate::store::{Store, StoreError};
-use crate::{SegmentId, SessionId};
+use crate::{PasteArtifactLimits, SegmentId, SessionId};
+use protocol::PasteArtifactRef;
 use std::fs;
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::path::{Path, PathBuf};
@@ -109,6 +111,16 @@ impl FsStore {
             .join(format!("{segment_id}.trace.jsonl"))
     }
 
+    fn paste_artifact_dir(&self, session_id: SessionId) -> PathBuf {
+        self.session_dir(session_id).join("artifacts").join("paste")
+    }
+
+    #[cfg(test)]
+    fn paste_artifact_path(&self, session_id: SessionId, artifact_id: &str) -> PathBuf {
+        self.paste_artifact_dir(session_id)
+            .join(format!("{artifact_id}.json"))
+    }
+
     fn append_line(&self, path: &Path, line: &str) -> Result<(), StoreError> {
         let _guard = self
             .append_lock
@@ -350,6 +362,33 @@ impl Store for FsStore {
         Ok(complete.lines().filter(|l| !l.trim().is_empty()).count())
     }
 
+    fn write_paste_artifact(
+        &self,
+        session_id: SessionId,
+        source_entry_id: &str,
+        content: &str,
+        limits: PasteArtifactLimits,
+    ) -> Result<PasteArtifactRef, StoreError> {
+        let _guard = self
+            .append_lock
+            .lock()
+            .map_err(|_| std::io::Error::other("session store append lock was poisoned"))?;
+        write_to_dir(
+            &self.paste_artifact_dir(session_id),
+            source_entry_id,
+            content,
+            limits,
+        )
+    }
+
+    fn read_paste_artifact(
+        &self,
+        session_id: SessionId,
+        artifact_id: &str,
+    ) -> Result<(PasteArtifactRef, String), StoreError> {
+        read_from_dir(&self.paste_artifact_dir(session_id), artifact_id)
+    }
+
     fn append_trace(
         &self,
         session_id: SessionId,
@@ -398,4 +437,146 @@ mod tests {
         store.create_segment(session_id, segment_id, &[]).unwrap();
         assert!(store.session_modified_at(session_id).unwrap().is_some());
     }
+
+    #[test]
+    fn paste_artifacts_are_atomic_integrity_checked_and_session_scoped() {
+        let tmp = tempfile::TempDir::new().unwrap();
+        let store = FsStore::new(tmp.path()).unwrap();
+        let owner = new_session_id();
+        let other = new_session_id();
+        let content = "αβγ\nsecond line\n";
+        let reference = store
+            .write_paste_artifact(owner, "entry-1", content, PasteArtifactLimits::default())
+            .unwrap();
+
+        assert_eq!(reference.byte_len, content.len() as u64);
+        assert!(reference.created_at_ms > 0);
+        assert_eq!(
+            reference.media_type,
+            protocol::PasteArtifactMediaType::TextPlainUtf8
+        );
+        assert_eq!(
+            reference.availability,
+            protocol::PasteArtifactAvailability::Available
+        );
+        assert_eq!(reference.char_count, content.chars().count() as u64);
+        assert_eq!(reference.source_entry_id, "entry-1");
+        assert_eq!(
+            store
+                .read_paste_artifact(owner, &reference.artifact_id)
+                .unwrap()
+                .1,
+            content
+        );
+        assert!(matches!(
+            store.read_paste_artifact(other, &reference.artifact_id),
+            Err(StoreError::PasteArtifactNotFound(_))
+        ));
+        assert!(
+            self::fs::read_dir(store.paste_artifact_dir(owner))
+                .unwrap()
+                .all(|entry| !entry
+                    .unwrap()
+                    .file_name()
+                    .to_string_lossy()
+                    .ends_with(".tmp"))
+        );
+        let very_large = "z".repeat(1024 * 1024);
+        let very_large_ref = store
+            .write_paste_artifact(
+                owner,
+                "entry-2",
+                &very_large,
+                PasteArtifactLimits::default(),
+            )
+            .unwrap();
+        assert_eq!(
+            store
+                .read_paste_artifact(owner, &very_large_ref.artifact_id)
+                .unwrap()
+                .1,
+            very_large
+        );
+    }
+
+    #[test]
+    fn concurrent_paste_writes_atomically_enforce_aggregate_caps() {
+        let tmp = tempfile::TempDir::new().unwrap();
+        let session_id = new_session_id();
+        let barrier = std::sync::Arc::new(std::sync::Barrier::new(3));
+        let limits = PasteArtifactLimits {
+            max_artifact_bytes: 4,
+            max_session_bytes: 8,
+            max_session_artifacts: 1,
+        };
+        let mut handles = Vec::new();
+        for entry_id in ["entry-1", "entry-2"] {
+            let root = tmp.path().to_path_buf();
+            let barrier = barrier.clone();
+            handles.push(std::thread::spawn(move || {
+                let store = FsStore::new(root).unwrap();
+                barrier.wait();
+                store.write_paste_artifact(session_id, entry_id, "1234", limits)
+            }));
+        }
+        barrier.wait();
+        let results = handles
+            .into_iter()
+            .map(|handle| handle.join().unwrap())
+            .collect::<Vec<_>>();
+        assert_eq!(results.iter().filter(|result| result.is_ok()).count(), 1);
+        assert_eq!(
+            results
+                .iter()
+                .filter(|result| matches!(result, Err(StoreError::PasteArtifactLimit(_))))
+                .count(),
+            1
+        );
+        assert_eq!(
+            std::fs::read_dir(
+                FsStore::new(tmp.path())
+                    .unwrap()
+                    .paste_artifact_dir(session_id)
+            )
+            .unwrap()
+            .filter_map(Result::ok)
+            .filter(
+                |entry| entry.path().extension().and_then(|value| value.to_str()) == Some("json")
+            )
+            .count(),
+            1
+        );
+    }
+
+    #[test]
+    fn paste_artifact_limits_and_corruption_fail_closed() {
+        let tmp = tempfile::TempDir::new().unwrap();
+        let store = FsStore::new(tmp.path()).unwrap();
+        let session_id = new_session_id();
+        let limits = PasteArtifactLimits {
+            max_artifact_bytes: 5,
+            max_session_bytes: 8,
+            max_session_artifacts: 2,
+        };
+        let first = store
+            .write_paste_artifact(session_id, "entry-1", "1234", limits)
+            .unwrap();
+        assert!(matches!(
+            store.write_paste_artifact(session_id, "entry-2", "56789", limits),
+            Err(StoreError::PasteArtifactLimit(_))
+        ));
+        assert!(matches!(
+            store.write_paste_artifact(session_id, "entry-2", "5678", limits),
+            Ok(_)
+        ));
+        std::fs::write(
+            store.paste_artifact_path(session_id, &first.artifact_id),
+            b"{}",
+        )
+        .unwrap();
+        assert!(matches!(
+            store.read_paste_artifact(session_id, &first.artifact_id),
+            Err(StoreError::Serde(_)) | Err(StoreError::PasteArtifactIntegrity(_))
+        ));
+    }
 }

crates/session-store/src/lib.rs

@@ -35,6 +35,7 @@ pub mod fs_store;
 pub mod history;
 mod legacy_session_log;
 pub mod logged_item;
+mod paste_artifact;
 pub mod public_snapshot;
 pub mod segment;
 pub mod segment_log;
@@ -53,6 +54,7 @@ pub use history::{
     LoggedWorkerSubject,
 };
 pub use logged_item::{LoggedContentPart, LoggedItem, LoggedRole, from_logged, to_logged};
+pub use paste_artifact::PasteArtifactLimits;
 pub use segment::{
     SegmentStartState, append_entry, append_system_item, classify_logged_history_entry,
     create_compacted_segment, create_segment, create_segment_with_ids, ensure_head_or_fork, fork,

crates/session-store/src/paste_artifact.rs

@@ -0,0 +1,186 @@
+//! Session-owned storage for large pasted-input artifacts.
+
+use std::fs;
+use std::io::Write as _;
+use std::path::Path;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use fs4::fs_std::FileExt;
+use protocol::{PasteArtifactAvailability, PasteArtifactMediaType, PasteArtifactRef};
+use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
+
+use crate::StoreError;
+
+/// Bounded storage policy applied before a large paste becomes durable input.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct PasteArtifactLimits {
+    pub max_artifact_bytes: u64,
+    pub max_session_bytes: u64,
+    pub max_session_artifacts: u64,
+}
+
+impl Default for PasteArtifactLimits {
+    fn default() -> Self {
+        Self {
+            max_artifact_bytes: 8 * 1024 * 1024,
+            max_session_bytes: 64 * 1024 * 1024,
+            max_session_artifacts: 1_024,
+        }
+    }
+}
+
+/// Integrity-bearing on-disk record. The body and metadata are committed in one
+/// atomic file replacement so readers never observe a half-written artifact.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub(crate) struct StoredPasteArtifact {
+    pub reference: PasteArtifactRef,
+    pub content: String,
+}
+
+pub(crate) fn write_to_dir(
+    artifact_dir: &Path,
+    source_entry_id: &str,
+    content: &str,
+    limits: PasteArtifactLimits,
+) -> Result<PasteArtifactRef, StoreError> {
+    let byte_len = content.len() as u64;
+    if byte_len > limits.max_artifact_bytes {
+        return Err(StoreError::PasteArtifactLimit(format!(
+            "artifact has {byte_len} bytes; maximum is {}",
+            limits.max_artifact_bytes
+        )));
+    }
+    fs::create_dir_all(artifact_dir)?;
+    let aggregate_lock = fs::OpenOptions::new()
+        .create(true)
+        .read(true)
+        .write(true)
+        .open(artifact_dir.join(".aggregate.lock"))?;
+    FileExt::lock_exclusive(&aggregate_lock)?;
+    let mut aggregate = 0_u64;
+    let mut artifact_count = 0_u64;
+    for entry in fs::read_dir(artifact_dir)? {
+        let path = entry?.path();
+        if path.extension().and_then(|value| value.to_str()) != Some("json") {
+            continue;
+        }
+        let stored: StoredPasteArtifact = serde_json::from_slice(&fs::read(&path)?)?;
+        verify(&stored, &stored.reference.artifact_id)?;
+        artifact_count = artifact_count.checked_add(1).ok_or_else(|| {
+            StoreError::PasteArtifactLimit("session artifact count overflow".to_string())
+        })?;
+        aggregate = aggregate
+            .checked_add(stored.reference.byte_len)
+            .ok_or_else(|| {
+                StoreError::PasteArtifactLimit("session aggregate size overflow".to_string())
+            })?;
+    }
+    let projected = aggregate.checked_add(byte_len).ok_or_else(|| {
+        StoreError::PasteArtifactLimit("session aggregate size overflow".to_string())
+    })?;
+    if projected > limits.max_session_bytes {
+        return Err(StoreError::PasteArtifactLimit(format!(
+            "session artifacts would use {projected} bytes; maximum is {}",
+            limits.max_session_bytes
+        )));
+    }
+    if artifact_count >= limits.max_session_artifacts {
+        return Err(StoreError::PasteArtifactLimit(format!(
+            "session already has {artifact_count} artifacts; maximum is {}",
+            limits.max_session_artifacts
+        )));
+    }
+
+    let artifact_id = uuid::Uuid::now_v7().to_string();
+    let created_at_ms = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map_err(|error| StoreError::PasteArtifactIntegrity(error.to_string()))?
+        .as_millis() as u64;
+    let reference = PasteArtifactRef {
+        artifact_id: artifact_id.clone(),
+        created_at_ms,
+        media_type: PasteArtifactMediaType::TextPlainUtf8,
+        availability: PasteArtifactAvailability::Available,
+        byte_len,
+        char_count: content.chars().count() as u64,
+        line_count: line_count(content),
+        sha256: sha256_hex(content),
+        source_entry_id: source_entry_id.to_string(),
+    };
+    let bytes = serde_json::to_vec(&StoredPasteArtifact {
+        reference: reference.clone(),
+        content: content.to_string(),
+    })?;
+    let target = artifact_dir.join(format!("{artifact_id}.json"));
+    let temporary = artifact_dir.join(format!(".{artifact_id}.tmp"));
+    let mut file = fs::OpenOptions::new()
+        .create_new(true)
+        .write(true)
+        .open(&temporary)?;
+    if let Err(error) = file.write_all(&bytes).and_then(|_| file.sync_all()) {
+        let _ = fs::remove_file(&temporary);
+        return Err(error.into());
+    }
+    if let Err(error) = fs::rename(&temporary, &target) {
+        let _ = fs::remove_file(&temporary);
+        return Err(error.into());
+    }
+    if let Ok(directory) = fs::File::open(artifact_dir) {
+        directory.sync_all()?;
+    }
+    Ok(reference)
+}
+
+pub(crate) fn read_from_dir(
+    artifact_dir: &Path,
+    artifact_id: &str,
+) -> Result<(PasteArtifactRef, String), StoreError> {
+    let parsed = uuid::Uuid::parse_str(artifact_id)
+        .map_err(|_| StoreError::PasteArtifactNotFound(artifact_id.to_string()))?;
+    if parsed.to_string() != artifact_id {
+        return Err(StoreError::PasteArtifactNotFound(artifact_id.to_string()));
+    }
+    let path = artifact_dir.join(format!("{artifact_id}.json"));
+    let bytes = match fs::read(path) {
+        Ok(bytes) => bytes,
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
+            return Err(StoreError::PasteArtifactNotFound(artifact_id.to_string()));
+        }
+        Err(error) => return Err(error.into()),
+    };
+    let stored: StoredPasteArtifact = serde_json::from_slice(&bytes)?;
+    verify(&stored, artifact_id)?;
+    Ok((stored.reference, stored.content))
+}
+
+fn verify(stored: &StoredPasteArtifact, artifact_id: &str) -> Result<(), StoreError> {
+    let actual_digest = sha256_hex(&stored.content);
+    if stored.reference.artifact_id != artifact_id
+        || stored.reference.created_at_ms == 0
+        || stored.reference.media_type != PasteArtifactMediaType::TextPlainUtf8
+        || stored.reference.availability != PasteArtifactAvailability::Available
+        || stored.reference.byte_len != stored.content.len() as u64
+        || stored.reference.char_count != stored.content.chars().count() as u64
+        || stored.reference.line_count != line_count(&stored.content)
+        || stored.reference.sha256 != actual_digest
+    {
+        return Err(StoreError::PasteArtifactIntegrity(artifact_id.to_string()));
+    }
+    Ok(())
+}
+
+fn sha256_hex(content: &str) -> String {
+    Sha256::digest(content.as_bytes())
+        .iter()
+        .map(|byte| format!("{byte:02x}"))
+        .collect()
+}
+
+fn line_count(content: &str) -> u64 {
+    if content.is_empty() {
+        0
+    } else {
+        content.lines().count().max(1) as u64
+    }
+}

crates/session-store/src/store.rs

@@ -13,7 +13,8 @@
 
 use crate::event_trace::TraceEntry;
 use crate::segment_log::LogEntry;
-use crate::{SegmentId, SessionId};
+use crate::{PasteArtifactLimits, SegmentId, SessionId};
+use protocol::PasteArtifactRef;
 
 /// Errors from the persistence store.
 #[derive(Debug, thiserror::Error)]
@@ -29,6 +30,18 @@ pub enum StoreError {
 
     #[error("log corrupted at line {line}: {message}")]
     Corrupt { line: usize, message: String },
+
+    #[error("paste artifact storage is unavailable")]
+    PasteArtifactUnsupported,
+
+    #[error("paste artifact not found: {0}")]
+    PasteArtifactNotFound(String),
+
+    #[error("paste artifact integrity check failed: {0}")]
+    PasteArtifactIntegrity(String),
+
+    #[error("paste artifact size limit exceeded: {0}")]
+    PasteArtifactLimit(String),
 }
 
 /// Sync persistence backend for segment logs.
@@ -117,6 +130,26 @@ pub trait Store: Send + Sync {
         segment_id: SegmentId,
     ) -> Result<usize, StoreError>;
 
+    /// Store a large paste before its reference is committed to history.
+    fn write_paste_artifact(
+        &self,
+        _session_id: SessionId,
+        _source_entry_id: &str,
+        _content: &str,
+        _limits: PasteArtifactLimits,
+    ) -> Result<PasteArtifactRef, StoreError> {
+        Err(StoreError::PasteArtifactUnsupported)
+    }
+
+    /// Read and verify one artifact owned by `session_id`.
+    fn read_paste_artifact(
+        &self,
+        _session_id: SessionId,
+        _artifact_id: &str,
+    ) -> Result<(PasteArtifactRef, String), StoreError> {
+        Err(StoreError::PasteArtifactUnsupported)
+    }
+
     /// Append a trace entry to the debug event trace file.
     fn append_trace(
         &self,

crates/session-store/src/worker_metadata.rs

@@ -608,6 +608,24 @@ where
     ) -> Result<usize, crate::StoreError> {
         self.session_store.read_entry_count(session_id, segment_id)
     }
+    fn write_paste_artifact(
+        &self,
+        session_id: SessionId,
+        source_entry_id: &str,
+        content: &str,
+        limits: crate::PasteArtifactLimits,
+    ) -> Result<protocol::PasteArtifactRef, crate::StoreError> {
+        self.session_store
+            .write_paste_artifact(session_id, source_entry_id, content, limits)
+    }
+    fn read_paste_artifact(
+        &self,
+        session_id: SessionId,
+        artifact_id: &str,
+    ) -> Result<(protocol::PasteArtifactRef, String), crate::StoreError> {
+        self.session_store
+            .read_paste_artifact(session_id, artifact_id)
+    }
     fn append_trace(
         &self,
         session_id: SessionId,

crates/session-store/src/worker_session_store.rs

@@ -10,9 +10,11 @@
 //! every later operation must use that same ID.
 
 use crate::event_trace::TraceEntry;
+use crate::paste_artifact::{read_from_dir, write_to_dir};
 use crate::segment_log::LogEntry;
 use crate::store::{Store, StoreError};
-use crate::{SegmentId, SessionId};
+use crate::{PasteArtifactLimits, SegmentId, SessionId};
+use protocol::PasteArtifactRef;
 use serde::{Deserialize, Serialize};
 use std::fs::{self, File, OpenOptions};
 use std::io::{Read, Seek, SeekFrom, Write};
@@ -25,6 +27,7 @@ const PREVIOUS_SESSION_SCHEMA_VERSION: u32 = 2;
 const LEGACY_SESSION_SCHEMA_VERSION: u32 = 1;
 const SESSION_FILE: &str = "session.json";
 const SEGMENTS_DIR: &str = "segments";
+const PASTE_ARTIFACTS_DIR: &str = "artifacts/paste";
 
 #[derive(Clone)]
 pub struct WorkerSessionStore {
@@ -317,6 +320,35 @@ impl Store for WorkerSessionStore {
             .count())
     }
 
+    fn write_paste_artifact(
+        &self,
+        session_id: SessionId,
+        source_entry_id: &str,
+        content: &str,
+        limits: PasteArtifactLimits,
+    ) -> Result<PasteArtifactRef, StoreError> {
+        self.ensure_session(session_id, true)?;
+        let _guard = self
+            .append_lock
+            .lock()
+            .map_err(|_| std::io::Error::other("Worker Session append lock was poisoned"))?;
+        write_to_dir(
+            &self.root.join(PASTE_ARTIFACTS_DIR),
+            source_entry_id,
+            content,
+            limits,
+        )
+    }
+
+    fn read_paste_artifact(
+        &self,
+        session_id: SessionId,
+        artifact_id: &str,
+    ) -> Result<(PasteArtifactRef, String), StoreError> {
+        self.ensure_session(session_id, false)?;
+        read_from_dir(&self.root.join(PASTE_ARTIFACTS_DIR), artifact_id)
+    }
+
     fn append_trace(
         &self,
         session_id: SessionId,
@@ -601,6 +633,45 @@ mod tests {
         assert_eq!(store.list_sessions().unwrap(), vec![session_id]);
     }
 
+    #[test]
+    fn worker_session_store_keeps_paste_artifacts_inside_retention_root() {
+        let root = tempfile::tempdir().unwrap();
+        let store = WorkerSessionStore::new(root.path().join("session")).unwrap();
+        let session_id = new_session_id();
+        store
+            .create_segment(session_id, new_segment_id(), &[])
+            .unwrap();
+        let content = "large paste body\n終端\n";
+        let reference = store
+            .write_paste_artifact(
+                session_id,
+                "entry-1",
+                content,
+                PasteArtifactLimits::default(),
+            )
+            .unwrap();
+
+        assert!(
+            root.path()
+                .join(format!(
+                    "session/{PASTE_ARTIFACTS_DIR}/{}.json",
+                    reference.artifact_id
+                ))
+                .is_file()
+        );
+        assert_eq!(
+            store
+                .read_paste_artifact(session_id, &reference.artifact_id)
+                .unwrap()
+                .1,
+            content
+        );
+        assert!(matches!(
+            store.read_paste_artifact(new_session_id(), &reference.artifact_id),
+            Err(StoreError::Corrupt { .. })
+        ));
+    }
+
     #[test]
     fn schema_v1_logs_are_rewritten_and_promoted_to_v3() {
         let root = tempfile::tempdir().unwrap();

crates/tui/src/input.rs

@@ -15,6 +15,64 @@ use ratatui::style::{Color, Style};
 use ratatui::text::{Line, Span};
 use unicode_width::UnicodeWidthChar;
 
+pub const MAX_PLAIN_TEXT_PASTE_CHARS: usize = 50;
+pub const MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES: usize = 3;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct PasteMeasurement {
+    pub chars: usize,
+    pub logical_lines: usize,
+}
+
+impl PasteMeasurement {
+    pub fn presentation(self) -> PastePresentation {
+        if self.chars <= MAX_PLAIN_TEXT_PASTE_CHARS
+            && self.logical_lines <= MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES
+        {
+            PastePresentation::Text
+        } else {
+            PastePresentation::Chip
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum PastePresentation {
+    Text,
+    Chip,
+}
+
+pub fn measure_paste(content: &str) -> PasteMeasurement {
+    PasteMeasurement {
+        chars: content.chars().count(),
+        logical_lines: logical_line_count(content),
+    }
+}
+
+/// Empty content has zero logical lines. Otherwise LF, lone CR, and CRLF each
+/// advance one line; a CRLF pair is one break rather than two.
+pub fn logical_line_count(content: &str) -> usize {
+    if content.is_empty() {
+        return 0;
+    }
+
+    let mut lines = 1;
+    let mut chars = content.chars().peekable();
+    while let Some(ch) = chars.next() {
+        match ch {
+            '\r' => {
+                if chars.peek() == Some(&'\n') {
+                    chars.next();
+                }
+                lines += 1;
+            }
+            '\n' => lines += 1,
+            _ => {}
+        }
+    }
+    lines
+}
+
 #[derive(Debug, Clone)]
 pub struct PasteRef {
     pub id: u32,
@@ -61,6 +119,7 @@ impl FlowRefAtom {
 pub enum Atom {
     Char(char),
     Paste(PasteRef),
+    PasteArtifact(protocol::PasteArtifactRef),
     FileRef(FileRefAtom),
     FlowRef(FlowRefAtom),
 }
@@ -72,6 +131,18 @@ impl Atom {
         match self {
             Atom::Char(_) => None,
             Atom::Paste(p) => Some((Style::default().fg(Color::Magenta), p.label())),
+            Atom::PasteArtifact(artifact) => Some((
+                Style::default().fg(Color::Magenta),
+                format!(
+                    "[Paste artifact {} | {} chars, {} lines, {}, {}, created {} ms]",
+                    artifact.artifact_id,
+                    artifact.char_count,
+                    artifact.line_count,
+                    artifact.media_type.as_str(),
+                    artifact.availability.as_str(),
+                    artifact.created_at_ms
+                ),
+            )),
             Atom::FileRef(r) => Some((Style::default().fg(Color::Cyan), r.label())),
             Atom::FlowRef(r) => Some((Style::default().fg(Color::Yellow), r.label())),
         }
@@ -102,7 +173,9 @@ enum WordKind {
 fn atom_class(atom: &Atom) -> AtomClass {
     match atom {
         Atom::Char(c) => char_class(*c),
-        Atom::Paste(_) | Atom::FileRef(_) | Atom::FlowRef(_) => AtomClass::Chip,
+        Atom::Paste(_) | Atom::PasteArtifact(_) | Atom::FileRef(_) | Atom::FlowRef(_) => {
+            AtomClass::Chip
+        }
     }
 }
 
@@ -190,6 +263,9 @@ impl InputBuffer {
                         content: content.clone(),
                     }));
                 }
+                protocol::Segment::PasteArtifact { artifact } => {
+                    self.atoms.push(Atom::PasteArtifact(artifact.clone()));
+                }
                 protocol::Segment::FileRef { path } => {
                     self.atoms
                         .push(Atom::FileRef(FileRefAtom { path: path.clone() }));
@@ -225,6 +301,13 @@ impl InputBuffer {
             match atom {
                 Atom::Char(c) => text.push(*c),
                 Atom::Paste(paste) => text.push_str(&paste.content),
+                Atom::PasteArtifact(artifact) => {
+                    text.push_str(&protocol::Segment::flatten_to_text(&[
+                        protocol::Segment::PasteArtifact {
+                            artifact: artifact.clone(),
+                        },
+                    ]))
+                }
                 Atom::FileRef(file) => text.push_str(&file.path),
                 Atom::FlowRef(flow) => text.push_str(&flow.selector),
             }
@@ -237,16 +320,20 @@ impl InputBuffer {
     }
 
     pub fn insert_paste(&mut self, content: String) {
+        let measurement = measure_paste(&content);
+        if measurement.presentation() == PastePresentation::Text {
+            self.insert_str(&content);
+            return;
+        }
+
         let id = self.next_paste_id;
         self.next_paste_id = self.next_paste_id.wrapping_add(1);
-        let chars = content.chars().count();
-        let lines = content.lines().count().max(1);
         self.atoms.insert(
             self.cursor,
             Atom::Paste(PasteRef {
                 id,
-                chars,
-                lines,
+                chars: measurement.chars,
+                lines: measurement.logical_lines,
                 content,
             }),
         );
@@ -395,80 +482,78 @@ impl InputBuffer {
         self.cursor = 0;
     }
 
-    pub fn move_home(&mut self) {
-        while self.cursor > 0 {
-            if matches!(self.atoms[self.cursor - 1], Atom::Char('\n')) {
-                break;
-            }
-            self.cursor -= 1;
+    fn logical_line_ranges(&self) -> Vec<(usize, usize)> {
+        let mut ranges = Vec::new();
+        let mut start = 0;
+        let mut index = 0;
+        while index < self.atoms.len() {
+            let break_len = match self.atoms[index] {
+                Atom::Char('\r') => {
+                    if matches!(self.atoms.get(index + 1), Some(Atom::Char('\n'))) {
+                        2
+                    } else {
+                        1
+                    }
+                }
+                Atom::Char('\n') => 1,
+                _ => {
+                    index += 1;
+                    continue;
+                }
+            };
+            ranges.push((start, index));
+            index += break_len;
+            start = index;
         }
+        ranges.push((start, self.atoms.len()));
+        ranges
+    }
+
+    fn logical_line_and_col(&self) -> (Vec<(usize, usize)>, usize, usize) {
+        let ranges = self.logical_line_ranges();
+        for (line, &(start, end)) in ranges.iter().enumerate() {
+            if self.cursor <= end {
+                return (ranges, line, self.cursor.saturating_sub(start));
+            }
+            if let Some(&(next_start, _)) = ranges.get(line + 1)
+                && self.cursor < next_start
+            {
+                return (ranges, line + 1, 0);
+            }
+        }
+        let line = ranges.len().saturating_sub(1);
+        let col = self.cursor.saturating_sub(ranges[line].0);
+        (ranges, line, col)
+    }
+
+    pub fn move_home(&mut self) {
+        let (ranges, line, _) = self.logical_line_and_col();
+        self.cursor = ranges[line].0;
     }
 
     pub fn move_end(&mut self) {
-        while self.cursor < self.atoms.len() {
-            if matches!(self.atoms[self.cursor], Atom::Char('\n')) {
-                break;
-            }
-            self.cursor += 1;
-        }
+        let (ranges, line, _) = self.logical_line_and_col();
+        self.cursor = ranges[line].1;
     }
 
     /// Move one logical line up, preserving column (atom count from
     /// current line start). No-op if already on the first line.
     pub fn move_up(&mut self) {
-        let (line_start, col) = self.line_start_and_col();
-        if line_start == 0 {
+        let (ranges, line, col) = self.logical_line_and_col();
+        if line == 0 {
             return;
         }
-        // `atoms[line_start - 1]` is the '\n' that opens the current
-        // line; find the previous line's start.
-        let prev_end = line_start - 1;
-        let mut prev_start = 0;
-        for i in (0..prev_end).rev() {
-            if matches!(self.atoms[i], Atom::Char('\n')) {
-                prev_start = i + 1;
-                break;
-            }
-        }
-        let prev_len = prev_end - prev_start;
-        self.cursor = prev_start + col.min(prev_len);
+        let (start, end) = ranges[line - 1];
+        self.cursor = start + col.min(end - start);
     }
 
     /// Move one logical line down, preserving column.
     pub fn move_down(&mut self) {
-        let (line_start, col) = self.line_start_and_col();
-        // End of current line.
-        let mut cur_end = self.atoms.len();
-        for i in line_start..self.atoms.len() {
-            if matches!(self.atoms[i], Atom::Char('\n')) {
-                cur_end = i;
-                break;
-            }
-        }
-        if cur_end == self.atoms.len() {
-            return; // no next line
-        }
-        let next_start = cur_end + 1;
-        let mut next_end = self.atoms.len();
-        for i in next_start..self.atoms.len() {
-            if matches!(self.atoms[i], Atom::Char('\n')) {
-                next_end = i;
-                break;
-            }
-        }
-        let next_len = next_end - next_start;
-        self.cursor = next_start + col.min(next_len);
-    }
-
-    fn line_start_and_col(&self) -> (usize, usize) {
-        let mut start = 0;
-        for i in (0..self.cursor).rev() {
-            if matches!(self.atoms[i], Atom::Char('\n')) {
-                start = i + 1;
-                break;
-            }
-        }
-        (start, self.cursor - start)
+        let (ranges, line, col) = self.logical_line_and_col();
+        let Some(&(start, end)) = ranges.get(line + 1) else {
+            return;
+        };
+        self.cursor = start + col.min(end - start);
     }
 
     /// Build the typed `Vec<Segment>` sent over the protocol. Adjacent
@@ -497,6 +582,12 @@ impl InputBuffer {
                         content: p.content.clone(),
                     });
                 }
+                Atom::PasteArtifact(artifact) => {
+                    flush_text(&mut buf, &mut out);
+                    out.push(protocol::Segment::PasteArtifact {
+                        artifact: artifact.clone(),
+                    });
+                }
                 Atom::FileRef(r) => {
                     flush_text(&mut buf, &mut out);
                     out.push(protocol::Segment::FileRef {
@@ -535,6 +626,7 @@ impl InputBuffer {
         let mut cursor_row: u16 = 0;
         let mut cursor_col: u16 = 0;
         let mut cursor_set = false;
+        let mut previous_was_cr = false;
 
         // Record cursor once, at the point right before `atom` would be
         // placed — accounting for a wrap that the atom itself will cause.
@@ -558,7 +650,7 @@ impl InputBuffer {
         for (i, atom) in self.atoms.iter().enumerate() {
             if !cursor_set && i == self.cursor {
                 let leading = match atom {
-                    Atom::Char('\n') => 0,
+                    Atom::Char('\n' | '\r') => 0,
                     Atom::Char(c) => UnicodeWidthChar::width(*c).unwrap_or(0),
                     other => other
                         .chip()
@@ -573,6 +665,21 @@ impl InputBuffer {
             }
 
             match atom {
+                Atom::Char('\r') => {
+                    flush_pending(
+                        &mut pending,
+                        &mut pending_width,
+                        pending_style,
+                        &mut rows,
+                        &mut row_width,
+                    );
+                    rows.push(Vec::new());
+                    row_width = 0;
+                    previous_was_cr = true;
+                }
+                Atom::Char('\n') if previous_was_cr => {
+                    previous_was_cr = false;
+                }
                 Atom::Char('\n') => {
                     flush_pending(
                         &mut pending,
@@ -583,8 +690,10 @@ impl InputBuffer {
                     );
                     rows.push(Vec::new());
                     row_width = 0;
+                    previous_was_cr = false;
                 }
                 Atom::Char(c) => {
+                    previous_was_cr = false;
                     let cw = UnicodeWidthChar::width(*c).unwrap_or(0);
                     if pending_style != text_style && !pending.is_empty() {
                         flush_pending(
@@ -608,6 +717,7 @@ impl InputBuffer {
                     );
                 }
                 other => {
+                    previous_was_cr = false;
                     let (chip_style, label) = other.chip().expect("non-char atom has a chip");
                     if pending_style != chip_style && !pending.is_empty() {
                         flush_pending(
@@ -848,6 +958,161 @@ mod render_viewport_tests {
     }
 }
 
+#[cfg(test)]
+mod paste_policy_tests {
+    use super::*;
+    use protocol::Segment;
+    use serde::Deserialize;
+
+    #[derive(Debug, Deserialize)]
+    struct Fixture {
+        max_plain_text_chars: usize,
+        max_plain_text_logical_lines: usize,
+        cases: Vec<FixtureCase>,
+    }
+
+    #[derive(Debug, Deserialize)]
+    struct FixtureCase {
+        name: String,
+        parts: Vec<FixturePart>,
+        char_count: usize,
+        logical_line_count: usize,
+        presentation: FixturePresentation,
+    }
+
+    #[derive(Debug, Deserialize)]
+    struct FixturePart {
+        value: String,
+        repeat: usize,
+    }
+
+    #[derive(Debug, Deserialize, PartialEq, Eq)]
+    #[serde(rename_all = "lowercase")]
+    enum FixturePresentation {
+        Text,
+        Chip,
+    }
+
+    fn fixture() -> Fixture {
+        serde_json::from_str(include_str!(
+            "../../../tests/fixtures/composer-paste-policy.json"
+        ))
+        .expect("shared composer paste policy fixture must be valid")
+    }
+
+    fn fixture_content(case: &FixtureCase) -> String {
+        case.parts
+            .iter()
+            .map(|part| part.value.repeat(part.repeat))
+            .collect()
+    }
+
+    #[test]
+    fn tui_follows_shared_paste_presentation_contract() {
+        let fixture = fixture();
+        assert_eq!(fixture.max_plain_text_chars, MAX_PLAIN_TEXT_PASTE_CHARS);
+        assert_eq!(
+            fixture.max_plain_text_logical_lines,
+            MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES
+        );
+
+        for case in fixture.cases {
+            let content = fixture_content(&case);
+            let measurement = measure_paste(&content);
+            let expected_presentation = match case.presentation {
+                FixturePresentation::Text => PastePresentation::Text,
+                FixturePresentation::Chip => PastePresentation::Chip,
+            };
+            assert_eq!(measurement.chars, case.char_count, "{} chars", case.name);
+            assert_eq!(
+                measurement.logical_lines, case.logical_line_count,
+                "{} logical lines",
+                case.name
+            );
+            assert_eq!(
+                measurement.presentation(),
+                expected_presentation,
+                "{} presentation",
+                case.name
+            );
+        }
+    }
+
+    #[test]
+    fn short_paste_is_editable_text_at_the_cursor() {
+        let mut buffer = InputBuffer::new();
+        buffer.insert_str("ac");
+        buffer.move_left();
+        buffer.insert_paste("b".to_owned());
+
+        assert_eq!(buffer.plain_text(), "abc");
+        assert!(
+            buffer
+                .atoms
+                .iter()
+                .all(|atom| matches!(atom, Atom::Char(_)))
+        );
+        assert_eq!(
+            buffer.submit_segments(),
+            vec![Segment::text("abc".to_owned())]
+        );
+    }
+
+    #[test]
+    fn short_multiline_paste_preserves_original_line_endings_as_text() {
+        let content = "ab\r\ncd\ref";
+        let mut buffer = InputBuffer::new();
+        buffer.insert_paste(content.to_owned());
+
+        assert_eq!(buffer.plain_text(), content);
+        assert!(
+            buffer
+                .atoms
+                .iter()
+                .all(|atom| matches!(atom, Atom::Char(_)))
+        );
+        assert_eq!(
+            buffer.submit_segments(),
+            vec![Segment::text(content.to_owned())]
+        );
+
+        let rendered: Vec<String> = buffer
+            .render(80)
+            .lines
+            .iter()
+            .map(|line| {
+                line.spans
+                    .iter()
+                    .map(|span| span.content.as_ref())
+                    .collect()
+            })
+            .collect();
+        assert_eq!(rendered, vec!["ab", "cd", "ef"]);
+
+        buffer.move_up();
+        assert_eq!(buffer.cursor, 6);
+        buffer.move_up();
+        assert_eq!(buffer.cursor, 2);
+        buffer.move_down();
+        assert_eq!(buffer.cursor, 6);
+        buffer.move_home();
+        assert_eq!(buffer.cursor, 4);
+        buffer.move_end();
+        assert_eq!(buffer.cursor, 6);
+    }
+
+    #[test]
+    fn empty_paste_is_a_noop() {
+        let mut buffer = InputBuffer::new();
+        buffer.insert_str("unchanged");
+        let paste_id = buffer.next_paste_id;
+        buffer.insert_paste(String::new());
+
+        assert_eq!(buffer.plain_text(), "unchanged");
+        assert_eq!(buffer.next_paste_id, paste_id);
+    }
+}
+
 #[cfg(test)]
 mod submit_segments_tests {
     use super::*;
@@ -873,7 +1138,8 @@ mod submit_segments_tests {
         for c in "see ".chars() {
             buf.insert_char(c);
         }
-        buf.insert_paste("line1\nline2".into());
+        let pasted = "line1\nline2\nline3\nline4";
+        buf.insert_paste(pasted.into());
         for c in " end".chars() {
             buf.insert_char(c);
         }
@@ -890,9 +1156,9 @@ mod submit_segments_tests {
                 content,
                 ..
             } => {
-                assert_eq!(content, "line1\nline2");
-                assert_eq!(*chars, "line1\nline2".chars().count() as u32);
-                assert_eq!(*lines, 2);
+                assert_eq!(content, pasted);
+                assert_eq!(*chars, pasted.chars().count() as u32);
+                assert_eq!(*lines, 4);
             }
             other => panic!("expected Paste, got {other:?}"),
         }
@@ -902,6 +1168,45 @@ mod submit_segments_tests {
         }
     }
 
+    #[test]
+    fn restored_direct_paste_remains_a_typed_segment_without_reclassification() {
+        let original = Segment::Paste {
+            id: 7,
+            chars: 1,
+            lines: 1,
+            content: "x".to_owned(),
+        };
+        let mut buf = InputBuffer::new();
+        buf.replace_with_segments(std::slice::from_ref(&original));
+
+        assert_eq!(buf.submit_segments(), vec![original]);
+    }
+
+    #[test]
+    fn restored_paste_artifact_remains_a_typed_segment() {
+        let artifact = protocol::PasteArtifactRef {
+            artifact_id: "019ca7c8-57b6-7f05-8edf-524147aba7b2".to_string(),
+            created_at_ms: 1_700_000_000_000,
+            media_type: protocol::PasteArtifactMediaType::TextPlainUtf8,
+            availability: protocol::PasteArtifactAvailability::Available,
+            byte_len: 65_536,
+            char_count: 65_530,
+            line_count: 200,
+            sha256: "a".repeat(64),
+            source_entry_id: "entry-1".to_string(),
+        };
+        let original = Segment::PasteArtifact {
+            artifact: artifact.clone(),
+        };
+        let mut buf = InputBuffer::new();
+        buf.replace_with_segments(std::slice::from_ref(&original));
+
+        assert_eq!(
+            buf.submit_segments(),
+            vec![Segment::PasteArtifact { artifact }]
+        );
+    }
+
     #[test]
     fn empty_buffer_yields_empty_segments() {
         let buf = InputBuffer::new();
@@ -911,7 +1216,7 @@ mod submit_segments_tests {
     #[test]
     fn leading_paste_does_not_emit_empty_text() {
         let mut buf = InputBuffer::new();
-        buf.insert_paste("X".into());
+        buf.insert_paste("X".repeat(MAX_PLAIN_TEXT_PASTE_CHARS + 1));
         let segs = buf.submit_segments();
         assert_eq!(segs.len(), 1);
         assert!(matches!(segs[0], Segment::Paste { .. }));
@@ -1011,7 +1316,7 @@ mod completion_prefix_tests {
     #[test]
     fn trigger_after_chip_atom() {
         let mut buf = InputBuffer::new();
-        buf.insert_paste("X".into());
+        buf.insert_paste("X".repeat(MAX_PLAIN_TEXT_PASTE_CHARS + 1));
         for c in "@sr".chars() {
             buf.insert_char(c);
         }
@@ -1120,7 +1425,7 @@ mod word_motion_tests {
         for c in "foo ".chars() {
             buf.insert_char(c);
         }
-        buf.insert_paste("anything".into());
+        buf.insert_paste("anything".repeat(MAX_PLAIN_TEXT_PASTE_CHARS + 1));
         for c in " bar".chars() {
             buf.insert_char(c);
         }
@@ -1219,7 +1524,9 @@ mod word_motion_tests {
         for a in &buf.atoms {
             match a {
                 Atom::Char(c) => out.push(*c),
-                Atom::Paste(_) | Atom::FileRef(_) | Atom::FlowRef(_) => out.push_str("<P>"),
+                Atom::Paste(_) | Atom::PasteArtifact(_) | Atom::FileRef(_) | Atom::FlowRef(_) => {
+                    out.push_str("<P>")
+                }
             }
         }
         out
@@ -1277,7 +1584,7 @@ mod word_motion_tests {
         for c in "foo ".chars() {
             buf.insert_char(c);
         }
-        buf.insert_paste("anything".into());
+        buf.insert_paste("anything".repeat(MAX_PLAIN_TEXT_PASTE_CHARS + 1));
         for c in " bar".chars() {
             buf.insert_char(c);
         }

crates/tui/src/ui.rs

@@ -1296,6 +1296,18 @@ fn chip_span_for(seg: &Segment, fallback: Style) -> (Style, String) {
             Style::default().fg(Color::Magenta),
             format!("[Clipboard #{id} | {chars} chars, {line_count} lines]"),
         ),
+        Segment::PasteArtifact { artifact } => (
+            Style::default().fg(Color::Magenta),
+            format!(
+                "[Paste artifact {} | {} chars, {} lines, {}, {}, created {} ms]",
+                artifact.artifact_id,
+                artifact.char_count,
+                artifact.line_count,
+                artifact.media_type.as_str(),
+                artifact.availability.as_str(),
+                artifact.created_at_ms
+            ),
+        ),
         Segment::FileRef { path } => (Style::default().fg(Color::Cyan), format!("@{path}")),
         Segment::Flow { selector } => (
             Style::default().fg(Color::Yellow),
@@ -1314,6 +1326,15 @@ fn segment_display_text(seg: &Segment) -> String {
         Segment::Paste {
             id, chars, lines, ..
         } => format!("[Clipboard #{id} | {chars} chars, {lines} lines]"),
+        Segment::PasteArtifact { artifact } => format!(
+            "[Paste artifact {} | {} chars, {} lines, {}, {}, created {} ms]",
+            artifact.artifact_id,
+            artifact.char_count,
+            artifact.line_count,
+            artifact.media_type.as_str(),
+            artifact.availability.as_str(),
+            artifact.created_at_ms
+        ),
         Segment::FileRef { path } => format!("@{path}"),
         Segment::Flow { selector } => format!("[Flow: {selector}]"),
         Segment::Unknown => "[unknown segment]".to_owned(),

crates/worker/src/controller.rs

@@ -898,6 +898,20 @@ where
             crate::spawn::tool::ParentNotificationTarget::Buffer(worker.notify_buffer_handle())
         });
     let prompts = worker.prompts().clone();
+    let paste_store = worker.store().clone();
+    let paste_session_id = worker.session_id();
+    worker
+        .engine_mut()
+        .register_tool(crate::paste_artifact_tool::search_input_artifact_tool(
+            paste_store.clone(),
+            paste_session_id,
+        ));
+    worker
+        .engine_mut()
+        .register_tool(crate::paste_artifact_tool::read_input_artifact_tool(
+            paste_store,
+            paste_session_id,
+        ));
     // Resolve the existing Worker–Workdir binding into the domain provider.
     // Tools only consume the provider handle; they do not own its root, cwd,
     // scope, or lifecycle. No-workdir Workers expose no local tools.

crates/worker/src/lib.rs

@@ -9,6 +9,7 @@ pub mod hook;
 pub(crate) mod in_flight;
 pub mod ipc;
 pub mod model_client;
+mod paste_artifact_tool;
 pub mod prompt;
 pub mod runtime;
 pub mod runtime_command;

crates/worker/src/paste_artifact_tool.rs

@@ -0,0 +1,347 @@
+//! Bounded model-facing access to session-owned large paste artifacts.
+
+use std::sync::Arc;
+
+use agen::tool::{Tool, ToolDefinition, ToolError, ToolExecutionContext, ToolMeta, ToolOutput};
+use async_trait::async_trait;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+use session_store::{SessionId, Store, StoreError};
+
+const MAX_QUERY_BYTES: usize = 256;
+const DEFAULT_SEARCH_RESULTS: usize = 20;
+const MAX_SEARCH_RESULTS: usize = 100;
+const MAX_SNIPPET_CHARS: usize = 300;
+const DEFAULT_READ_BYTES: usize = 8 * 1024;
+const MAX_READ_BYTES: usize = 16 * 1024;
+
+const SEARCH_DESCRIPTION: &str = "Search one large pasted-input artifact owned by the current Worker. Returns bounded matching line snippets; never returns the whole artifact.";
+const READ_DESCRIPTION: &str = "Read a bounded UTF-8 byte range from one large pasted-input artifact owned by the current Worker. Use next_offset for repeated calls instead of requesting the whole artifact.";
+
+#[derive(Clone)]
+struct ArtifactAccess<St: Store + Clone> {
+    store: St,
+    session_id: SessionId,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+struct SearchInputArtifactInput {
+    /// Opaque artifact id from a large-paste history reference.
+    artifact_id: String,
+    /// Literal case-sensitive text to find.
+    query: String,
+    /// Maximum matching lines to return (1..=100).
+    max_results: Option<usize>,
+}
+
+#[derive(Debug, Serialize)]
+struct SearchInputArtifactOutput {
+    artifact_id: String,
+    matches: Vec<SearchMatch>,
+    truncated: bool,
+}
+
+#[derive(Debug, Serialize)]
+struct SearchMatch {
+    line: u64,
+    byte_offset: u64,
+    snippet: String,
+}
+
+struct SearchInputArtifactTool<St: Store + Clone> {
+    access: ArtifactAccess<St>,
+}
+
+#[async_trait]
+impl<St> Tool for SearchInputArtifactTool<St>
+where
+    St: Store + Clone + Send + Sync + 'static,
+{
+    async fn execute(
+        &self,
+        input_json: &str,
+        _context: ToolExecutionContext,
+    ) -> Result<ToolOutput, ToolError> {
+        let input: SearchInputArtifactInput =
+            serde_json::from_str(input_json).map_err(|error| {
+                ToolError::InvalidArgument(format!("invalid SearchInputArtifact input: {error}"))
+            })?;
+        if input.query.is_empty() || input.query.len() > MAX_QUERY_BYTES {
+            return Err(ToolError::InvalidArgument(
+                "query must contain 1..=256 UTF-8 bytes".to_string(),
+            ));
+        }
+        let max_results = input
+            .max_results
+            .unwrap_or(DEFAULT_SEARCH_RESULTS)
+            .clamp(1, MAX_SEARCH_RESULTS);
+        let (_, content) = self
+            .access
+            .store
+            .read_paste_artifact(self.access.session_id, &input.artifact_id)
+            .map_err(tool_store_error)?;
+        let mut matches = Vec::new();
+        let mut truncated = false;
+        let mut byte_offset = 0_u64;
+        for (index, raw_line) in content.split_inclusive('\n').enumerate() {
+            let line = raw_line.strip_suffix('\n').unwrap_or(raw_line);
+            if line.contains(&input.query) {
+                if matches.len() == max_results {
+                    truncated = true;
+                    break;
+                }
+                matches.push(SearchMatch {
+                    line: index as u64 + 1,
+                    byte_offset,
+                    snippet: truncate_chars(line, MAX_SNIPPET_CHARS),
+                });
+            }
+            byte_offset += raw_line.len() as u64;
+        }
+        json_output(
+            format!("Found {} matching pasted-input line(s).", matches.len()),
+            &SearchInputArtifactOutput {
+                artifact_id: input.artifact_id,
+                matches,
+                truncated,
+            },
+        )
+    }
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+struct ReadInputArtifactInput {
+    /// Opaque artifact id from a large-paste history reference.
+    artifact_id: String,
+    /// UTF-8 byte offset to start reading. Defaults to 0 and must be a character boundary.
+    offset: Option<u64>,
+    /// Maximum UTF-8 bytes to return (4..=16384). Defaults to 8192.
+    max_bytes: Option<usize>,
+}
+
+#[derive(Debug, Serialize)]
+struct ReadInputArtifactOutput {
+    artifact_id: String,
+    offset: u64,
+    content: String,
+    next_offset: Option<u64>,
+    truncated: bool,
+}
+
+struct ReadInputArtifactTool<St: Store + Clone> {
+    access: ArtifactAccess<St>,
+}
+
+#[async_trait]
+impl<St> Tool for ReadInputArtifactTool<St>
+where
+    St: Store + Clone + Send + Sync + 'static,
+{
+    async fn execute(
+        &self,
+        input_json: &str,
+        _context: ToolExecutionContext,
+    ) -> Result<ToolOutput, ToolError> {
+        let input: ReadInputArtifactInput = serde_json::from_str(input_json).map_err(|error| {
+            ToolError::InvalidArgument(format!("invalid ReadInputArtifact input: {error}"))
+        })?;
+        let offset = input.offset.unwrap_or(0);
+        let max_bytes = input
+            .max_bytes
+            .unwrap_or(DEFAULT_READ_BYTES)
+            .clamp(4, MAX_READ_BYTES);
+        let (_, content) = self
+            .access
+            .store
+            .read_paste_artifact(self.access.session_id, &input.artifact_id)
+            .map_err(tool_store_error)?;
+        let offset = usize::try_from(offset).map_err(|_| {
+            ToolError::InvalidArgument("offset exceeds the artifact size".to_string())
+        })?;
+        if offset > content.len() || !content.is_char_boundary(offset) {
+            return Err(ToolError::InvalidArgument(
+                "offset must be a UTF-8 character boundary within the artifact".to_string(),
+            ));
+        }
+        let mut end = offset.saturating_add(max_bytes).min(content.len());
+        while end > offset && !content.is_char_boundary(end) {
+            end -= 1;
+        }
+        let output = content[offset..end].to_string();
+        let next_offset = (end < content.len()).then_some(end as u64);
+        let truncated = next_offset.is_some();
+
+        json_output(
+            format!("Read {} pasted-input byte(s).", output.len()),
+            &ReadInputArtifactOutput {
+                artifact_id: input.artifact_id,
+                offset: offset as u64,
+                content: output,
+                next_offset,
+                truncated,
+            },
+        )
+    }
+}
+
+pub(crate) fn search_input_artifact_tool<St>(store: St, session_id: SessionId) -> ToolDefinition
+where
+    St: Store + Clone + Send + Sync + 'static,
+{
+    Arc::new(move || {
+        let schema = serde_json::to_value(schemars::schema_for!(SearchInputArtifactInput))
+            .unwrap_or_else(|_| serde_json::json!({}));
+        let meta = ToolMeta::new("SearchInputArtifact")
+            .description(SEARCH_DESCRIPTION)
+            .input_schema(schema);
+        let tool: Arc<dyn Tool> = Arc::new(SearchInputArtifactTool {
+            access: ArtifactAccess {
+                store: store.clone(),
+                session_id,
+            },
+        });
+        (meta, tool)
+    })
+}
+
+pub(crate) fn read_input_artifact_tool<St>(store: St, session_id: SessionId) -> ToolDefinition
+where
+    St: Store + Clone + Send + Sync + 'static,
+{
+    Arc::new(move || {
+        let schema = serde_json::to_value(schemars::schema_for!(ReadInputArtifactInput))
+            .unwrap_or_else(|_| serde_json::json!({}));
+        let meta = ToolMeta::new("ReadInputArtifact")
+            .description(READ_DESCRIPTION)
+            .input_schema(schema);
+        let tool: Arc<dyn Tool> = Arc::new(ReadInputArtifactTool {
+            access: ArtifactAccess {
+                store: store.clone(),
+                session_id,
+            },
+        });
+        (meta, tool)
+    })
+}
+
+fn json_output(summary: String, value: &impl Serialize) -> Result<ToolOutput, ToolError> {
+    let content = serde_json::to_string(value)
+        .map_err(|error| ToolError::ExecutionFailed(error.to_string()))?;
+    Ok(ToolOutput {
+        summary,
+        content: Some(content),
+        attachments: Vec::new(),
+    })
+}
+
+fn tool_store_error(error: StoreError) -> ToolError {
+    let message = match error {
+        StoreError::PasteArtifactNotFound(_) => "paste artifact not found",
+        StoreError::PasteArtifactIntegrity(_) | StoreError::Corrupt { .. } => {
+            "paste artifact failed its integrity check"
+        }
+        StoreError::PasteArtifactUnsupported => "paste artifact storage is unavailable",
+        _ => "paste artifact is unavailable",
+    };
+    ToolError::ExecutionFailed(message.to_string())
+}
+
+fn truncate_chars(value: &str, limit: usize) -> String {
+    let mut chars = value.chars();
+    let truncated = chars.by_ref().take(limit).collect::<String>();
+    if chars.next().is_some() {
+        format!("{truncated}…")
+    } else {
+        truncated
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use agen::tool::ToolExecutionContext;
+    use session_store::{FsStore, PasteArtifactLimits, Store, new_session_id};
+
+    use super::*;
+
+    #[tokio::test]
+    async fn search_and_read_are_bounded_and_owner_scoped() {
+        let temp = tempfile::TempDir::new().unwrap();
+        let store = FsStore::new(temp.path()).unwrap();
+        let owner = new_session_id();
+        let other = new_session_id();
+        let content = (0..700)
+            .map(|index| format!("line {index}: needle {}", "x".repeat(80)))
+            .collect::<Vec<_>>()
+            .join("\n");
+        let artifact = store
+            .write_paste_artifact(owner, "entry-1", &content, PasteArtifactLimits::default())
+            .unwrap();
+
+        let search = SearchInputArtifactTool {
+            access: ArtifactAccess {
+                store: store.clone(),
+                session_id: owner,
+            },
+        };
+        let searched = search
+            .execute(
+                &serde_json::json!({
+                    "artifact_id": artifact.artifact_id,
+                    "query": "needle",
+                    "max_results": 3
+                })
+                .to_string(),
+                ToolExecutionContext::default(),
+            )
+            .await
+            .unwrap();
+        let searched: serde_json::Value =
+            serde_json::from_str(searched.content.as_deref().unwrap()).unwrap();
+        assert_eq!(searched["matches"].as_array().unwrap().len(), 3);
+        assert_eq!(searched["truncated"], true);
+
+        let read = ReadInputArtifactTool {
+            access: ArtifactAccess {
+                store: store.clone(),
+                session_id: owner,
+            },
+        };
+        let read_output = read
+            .execute(
+                &serde_json::json!({
+                    "artifact_id": artifact.artifact_id,
+                    "offset": 2,
+                    "max_bytes": 999999
+                })
+                .to_string(),
+                ToolExecutionContext::default(),
+            )
+            .await
+            .unwrap();
+        let read_output: serde_json::Value =
+            serde_json::from_str(read_output.content.as_deref().unwrap()).unwrap();
+        assert!(read_output["content"].as_str().unwrap().len() <= MAX_READ_BYTES);
+        assert_eq!(read_output["truncated"], true);
+        assert!(read_output["next_offset"].as_u64().is_some());
+
+        let foreign = ReadInputArtifactTool {
+            access: ArtifactAccess {
+                store,
+                session_id: other,
+            },
+        };
+        let error = foreign
+            .execute(
+                &serde_json::json!({
+                    "artifact_id": artifact.artifact_id,
+                    "offset": 0,
+                    "max_bytes": 1
+                })
+                .to_string(),
+                ToolExecutionContext::default(),
+            )
+            .await
+            .unwrap_err();
+        assert!(error.to_string().contains("paste artifact not found"));
+    }
+}

crates/worker/src/session_history.rs

@@ -62,6 +62,7 @@ pub(crate) fn metadata(
     }
 }
 
+#[cfg(test)]
 pub(crate) fn history_entry(
     item: Item,
     origin: WorkerHistoryProvenance,
@@ -69,6 +70,21 @@ pub(crate) fn history_entry(
     HistoryEntry::new(item, metadata(origin, None))
 }
 
+pub(crate) fn history_entry_with_id(
+    item: Item,
+    entry_id: SessionHistoryEntryId,
+    origin: WorkerHistoryProvenance,
+) -> HistoryEntry<SessionHistoryMetadata> {
+    HistoryEntry::new(
+        item,
+        SessionHistoryMetadata {
+            entry_id,
+            origin,
+            derivation: None,
+        },
+    )
+}
+
 pub(crate) fn to_logged_history_entry(
     entry: &HistoryEntry<SessionHistoryMetadata>,
 ) -> LoggedHistoryEntry {

crates/worker/src/worker.rs

@@ -15,8 +15,8 @@ use agen::{
 };
 use arc_swap::ArcSwap;
 use session_store::{
-    LogEntry, PromptRenderProvenance, SegmentId, SessionExtension, SessionId, Store, StoreError,
-    SystemItem, segment_log,
+    LogEntry, PasteArtifactLimits, PromptRenderProvenance, SegmentId, SessionExtension, SessionId,
+    Store, StoreError, SystemItem, segment_log,
 };
 use session_store::{
     WorkerActiveSegmentRef, WorkerMetadata, WorkerMetadataStore, WorkerReclaimedChild,
@@ -25,10 +25,12 @@ use session_store::{
 use tracing::{info, warn};
 
 use crate::segment_log_sink::SegmentLogSink;
+#[cfg(test)]
+use crate::session_history::history_entry;
 use crate::session_history::{
-    SessionHistoryDerivation, SessionHistoryMetadata, WorkerHistoryProvenance, history_entry,
-    metadata as new_history_metadata, restore_history_entries, to_logged_history_entry,
-    worker_subject,
+    SessionHistoryDerivation, SessionHistoryEntryId, SessionHistoryMetadata,
+    WorkerHistoryProvenance, history_entry_with_id, metadata as new_history_metadata,
+    restore_history_entries, to_logged_history_entry, worker_subject,
 };
 
 use manifest::{
@@ -58,6 +60,7 @@ use crate::internal_worker::{
 };
 
 const COMPACTION_EXTENSION_DOMAIN: &str = "yoi.compaction";
+const LARGE_PASTE_INLINE_MAX_BYTES: usize = 32 * 1024;
 const WORKER_ORCHESTRATION_INSTRUCTION_ID: &str = "worker.orchestration";
 const WORKER_ORCHESTRATION_PROMPT_REF: &str = "common.worker_orchestration";
 
@@ -2797,7 +2800,15 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
         St: Clone + 'static,
         F: FnOnce(),
     {
-        let (input, pending_flow_state, flow_projection) = self.prepare_flow_input(input)?;
+        let (mut input, pending_flow_state, flow_projection) = self.prepare_flow_input(input)?;
+        let projected_entry_ids = if flow_projection.is_some() {
+            (0..input.len())
+                .map(|_| SessionHistoryEntryId::new())
+                .collect::<Vec<_>>()
+        } else {
+            vec![SessionHistoryEntryId::new()]
+        };
+        self.materialize_large_pastes(&mut input, &projected_entry_ids, flow_projection.is_some())?;
         if let Some(state) = pending_flow_state.as_ref() {
             let payload = serde_json::to_value(state).map_err(|error| {
                 WorkerError::FlowInput(format!("serialize Flow runtime state: {error}"))
@@ -2830,7 +2841,8 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
             trigger: protocol::InvokeKind::UserSend,
         })?;
 
-        let projected_input = self.projected_input_history(&input, flow_projection.as_ref());
+        let projected_input =
+            self.projected_input_history(&input, flow_projection.as_ref(), &projected_entry_ids);
 
         // Persist original typed segments together with the exact ordered
         // model-visible item+origin projection before any entry becomes live.
@@ -3064,17 +3076,61 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
         Ok(())
     }
 
+    fn materialize_large_pastes(
+        &self,
+        input: &mut [Segment],
+        projected_entry_ids: &[SessionHistoryEntryId],
+        one_entry_per_segment: bool,
+    ) -> Result<(), WorkerError> {
+        for (index, segment) in input.iter_mut().enumerate() {
+            if let Segment::PasteArtifact { artifact } = segment {
+                let (stored, _) = self
+                    .store
+                    .read_paste_artifact(self.session_id(), &artifact.artifact_id)?;
+                if &stored != artifact {
+                    return Err(WorkerError::Store(StoreError::PasteArtifactIntegrity(
+                        artifact.artifact_id.clone(),
+                    )));
+                }
+                continue;
+            }
+            let Segment::Paste { content, .. } = segment else {
+                continue;
+            };
+            if content.len() <= LARGE_PASTE_INLINE_MAX_BYTES {
+                continue;
+            }
+            let entry_index = if one_entry_per_segment { index } else { 0 };
+            let source_entry_id = projected_entry_ids
+                .get(entry_index)
+                .expect("projected input id exists for every paste")
+                .0
+                .as_str();
+            let artifact = self.store.write_paste_artifact(
+                self.session_id(),
+                source_entry_id,
+                content,
+                PasteArtifactLimits::default(),
+            )?;
+            *segment = Segment::PasteArtifact { artifact };
+        }
+        Ok(())
+    }
+
     fn projected_input_history(
         &self,
         input: &[Segment],
         flow_projection: Option<&PreparedFlowProjection>,
+        entry_ids: &[SessionHistoryEntryId],
     ) -> Vec<HistoryEntry<SessionHistoryMetadata>> {
         if let Some(flow) = flow_projection {
             return input
                 .iter()
-                .map(|segment| match segment {
-                    Segment::Flow { .. } => history_entry(
+                .zip(entry_ids)
+                .map(|(segment, entry_id)| match segment {
+                    Segment::Flow { .. } => history_entry_with_id(
                         Item::user_message(flow.instructions.clone()),
+                        entry_id.clone(),
                         WorkerHistoryProvenance::FlowInstruction {
                             selector: flow.selector.clone(),
                             definition_id: flow.definition_id.clone(),
@@ -3083,8 +3139,9 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
                             state_id: flow.state_id.clone(),
                         },
                     ),
-                    other => history_entry(
+                    other => history_entry_with_id(
                         Item::user_message(Segment::flatten_to_text(std::slice::from_ref(other))),
+                        entry_id.clone(),
                         // Current public submit transport does not carry a
                         // trusted account/Worker subject envelope. Fail closed
                         // instead of promoting role=user to HumanInput.
@@ -3094,8 +3151,12 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
                 .collect();
         }
 
-        vec![history_entry(
+        vec![history_entry_with_id(
             Item::user_message(Segment::flatten_to_text(input)),
+            entry_ids
+                .first()
+                .expect("projected Worker input always has one entry id")
+                .clone(),
             WorkerHistoryProvenance::LegacyUnknown,
         )]
     }
@@ -6405,6 +6466,11 @@ fn preview_segments(segments: &[Segment]) -> String {
         match segment {
             Segment::Text { content } => preview.push_str(content.trim()),
             Segment::Paste { content, .. } => preview.push_str(content.trim()),
+            Segment::PasteArtifact { artifact } => {
+                preview.push_str("[Large paste artifact: ");
+                preview.push_str(&artifact.artifact_id);
+                preview.push(']');
+            }
             Segment::FileRef { path } => {
                 preview.push('@');
                 preview.push_str(path);
@@ -7909,7 +7975,9 @@ mod build_summary_prompt_tests {
             FLOW_RUNTIME_EXTENSION_DOMAIN,
             serde_json::to_value(&state).unwrap(),
         );
-        let projected = worker.projected_input_history(&segments, projection.as_ref());
+        let projected_ids = vec![SessionHistoryEntryId::new(), SessionHistoryEntryId::new()];
+        let projected =
+            worker.projected_input_history(&segments, projection.as_ref(), &projected_ids);
         worker
             .commit_entry(LogEntry::AnnotatedUserInput {
                 ts: segment_log::now_millis(),
@@ -7981,6 +8049,144 @@ mod build_summary_prompt_tests {
         );
     }
 
+    #[tokio::test]
+    async fn large_paste_is_stored_before_compact_history_is_committed() {
+        let (_dir, worker) = rewind_test_worker().await;
+        let exact = "x".repeat(LARGE_PASTE_INLINE_MAX_BYTES);
+        let exact_ids = vec![SessionHistoryEntryId::new()];
+        let mut exact_input = vec![Segment::Paste {
+            id: 1,
+            chars: exact.len() as u32,
+            lines: 1,
+            content: exact.clone(),
+        }];
+        worker
+            .materialize_large_pastes(&mut exact_input, &exact_ids, false)
+            .unwrap();
+        assert!(matches!(&exact_input[0], Segment::Paste { content, .. } if content == &exact));
+        let mut empty_input = vec![Segment::Paste {
+            id: 0,
+            chars: 0,
+            lines: 0,
+            content: String::new(),
+        }];
+        worker
+            .materialize_large_pastes(&mut empty_input, &exact_ids, false)
+            .unwrap();
+        assert!(matches!(
+            &empty_input[0],
+            Segment::Paste { content, .. } if content.is_empty()
+        ));
+
+        let body = format!("{}\n終端\n", "多".repeat(12_000));
+        let entry_id = SessionHistoryEntryId::new();
+        let mut input = vec![Segment::Paste {
+            id: 2,
+            chars: body.chars().count() as u32,
+            lines: 3,
+            content: body.clone(),
+        }];
+        worker
+            .materialize_large_pastes(&mut input, std::slice::from_ref(&entry_id), false)
+            .unwrap();
+        let artifact = match &input[0] {
+            Segment::PasteArtifact { artifact } => artifact.clone(),
+            other => panic!("expected stored paste reference, got {other:?}"),
+        };
+        assert_eq!(artifact.source_entry_id, entry_id.0);
+        assert_eq!(artifact.byte_len, body.len() as u64);
+        assert_eq!(artifact.char_count, body.chars().count() as u64);
+        assert_eq!(
+            worker
+                .store
+                .read_paste_artifact(worker.session_id(), &artifact.artifact_id)
+                .unwrap()
+                .1,
+            body
+        );
+        worker
+            .materialize_large_pastes(&mut input, &[SessionHistoryEntryId::new()], false)
+            .unwrap();
+        assert!(matches!(
+            &input[0],
+            Segment::PasteArtifact { artifact: retained }
+                if retained.source_entry_id == artifact.source_entry_id
+        ));
+
+        let history = worker.projected_input_history(&input, None, &[entry_id]);
+        assert!(!history[0].item.as_text().unwrap().contains("終端"));
+        append_test_entry(
+            &worker,
+            LogEntry::Invoke {
+                ts: segment_log::now_millis(),
+                trigger: protocol::InvokeKind::UserSend,
+            },
+        );
+        worker
+            .commit_entry(LogEntry::AnnotatedUserInput {
+                ts: segment_log::now_millis(),
+                segments: input.clone(),
+                extensions: Vec::new(),
+                history: history.iter().map(to_logged_history_entry).collect(),
+            })
+            .unwrap();
+        let location = worker.segment_state.location();
+        let entries = worker
+            .store
+            .read_all(location.session_id, location.segment_id)
+            .unwrap();
+        let persisted = serde_json::to_string(&entries).unwrap();
+        assert!(!persisted.contains("終端"));
+        let state = session_store::collect_state(&entries);
+        assert!(matches!(
+            &state.user_segments[0][0],
+            Segment::PasteArtifact { artifact: restored }
+                if restored.artifact_id == artifact.artifact_id
+        ));
+    }
+
+    #[tokio::test]
+    async fn large_paste_storage_failure_commits_no_input() {
+        let temp = tempfile::TempDir::new().unwrap();
+        let store = session_store::FsStore::new(temp.path()).unwrap();
+        let mut worker = Worker::new(
+            minimal_manifest(),
+            Engine::<_, Mutable, SessionHistoryMetadata>::new_annotated(NoopClient),
+            store.clone(),
+            WorkerWorkspaceContext::unavailable(None, "test unavailable"),
+            WorkerFilesystemAuthority::None,
+            Scope::empty(),
+        )
+        .await
+        .unwrap();
+        worker.ensure_segment_head().unwrap();
+        std::fs::write(
+            temp.path()
+                .join(worker.session_id().to_string())
+                .join("artifacts"),
+            "block artifact directory creation",
+        )
+        .unwrap();
+        let result = worker
+            .run(vec![Segment::Paste {
+                id: 1,
+                chars: (LARGE_PASTE_INLINE_MAX_BYTES + 1) as u32,
+                lines: 1,
+                content: "x".repeat(LARGE_PASTE_INLINE_MAX_BYTES + 1),
+            }])
+            .await;
+        assert!(matches!(result, Err(WorkerError::Store(StoreError::Io(_)))));
+        let location = worker.segment_state.location();
+        let entries = store
+            .read_all(location.session_id, location.segment_id)
+            .unwrap();
+        assert!(
+            !entries
+                .iter()
+                .any(|entry| matches!(entry, LogEntry::AnnotatedUserInput { .. }))
+        );
+    }
+
     async fn rewind_test_worker() -> (
         tempfile::TempDir,
         Worker<NoopClient, session_store::FsStore>,

crates/worker/tests/controller_test.rs

@@ -613,7 +613,19 @@ async fn feature_flags_default_to_core_tool_surface_only() {
 
     let request = wait_for_captured_request(&client_for_assert).await;
     let names = request_tool_names(&request);
-    assert_eq!(names, vec!["Bash", "Edit", "Glob", "Grep", "Read", "Write"]);
+    assert_eq!(
+        names,
+        vec![
+            "Bash",
+            "Edit",
+            "Glob",
+            "Grep",
+            "Read",
+            "ReadInputArtifact",
+            "SearchInputArtifact",
+            "Write",
+        ]
+    );
     assert!(!names.iter().any(|name| name == "TaskCreate"));
     assert!(!names.iter().any(|name| name == "WebSearch"));
     assert!(!names.iter().any(|name| name == "SubWorkerSpawn"));

tests/fixtures/composer-paste-policy.json

@@ -0,0 +1,147 @@
+{
+  "max_plain_text_chars": 50,
+  "max_plain_text_logical_lines": 3,
+  "cases": [
+    {
+      "name": "empty",
+      "parts": [],
+      "char_count": 0,
+      "logical_line_count": 0,
+      "presentation": "text"
+    },
+    {
+      "name": "ascii_50",
+      "parts": [{ "value": "a", "repeat": 50 }],
+      "char_count": 50,
+      "logical_line_count": 1,
+      "presentation": "text"
+    },
+    {
+      "name": "ascii_51",
+      "parts": [{ "value": "a", "repeat": 51 }],
+      "char_count": 51,
+      "logical_line_count": 1,
+      "presentation": "chip"
+    },
+    {
+      "name": "three_lines_50_scalars",
+      "parts": [
+        { "value": "a\nb\n", "repeat": 1 },
+        { "value": "x", "repeat": 46 }
+      ],
+      "char_count": 50,
+      "logical_line_count": 3,
+      "presentation": "text"
+    },
+    {
+      "name": "four_lines_50_scalars",
+      "parts": [
+        { "value": "a\nb\nc\n", "repeat": 1 },
+        { "value": "x", "repeat": 44 }
+      ],
+      "char_count": 50,
+      "logical_line_count": 4,
+      "presentation": "chip"
+    },
+    {
+      "name": "four_lines_51_scalars",
+      "parts": [
+        { "value": "a\nb\nc\n", "repeat": 1 },
+        { "value": "x", "repeat": 45 }
+      ],
+      "char_count": 51,
+      "logical_line_count": 4,
+      "presentation": "chip"
+    },
+    {
+      "name": "two_lines_51_scalars",
+      "parts": [
+        { "value": "a\n", "repeat": 1 },
+        { "value": "x", "repeat": 49 }
+      ],
+      "char_count": 51,
+      "logical_line_count": 2,
+      "presentation": "chip"
+    },
+    {
+      "name": "four_lines_10_scalars",
+      "parts": [
+        { "value": "a\nb\nc\n", "repeat": 1 },
+        { "value": "x", "repeat": 4 }
+      ],
+      "char_count": 10,
+      "logical_line_count": 4,
+      "presentation": "chip"
+    },
+    {
+      "name": "japanese",
+      "parts": [{ "value": "日本語の貼り付け", "repeat": 1 }],
+      "char_count": 8,
+      "logical_line_count": 1,
+      "presentation": "text"
+    },
+    {
+      "name": "combining_marks_50_scalars",
+      "parts": [{ "value": "é", "repeat": 25 }],
+      "char_count": 50,
+      "logical_line_count": 1,
+      "presentation": "text"
+    },
+    {
+      "name": "unicode_scalar_50",
+      "parts": [{ "value": "🦀", "repeat": 50 }],
+      "char_count": 50,
+      "logical_line_count": 1,
+      "presentation": "text"
+    },
+    {
+      "name": "unicode_scalar_51",
+      "parts": [{ "value": "🦀", "repeat": 51 }],
+      "char_count": 51,
+      "logical_line_count": 1,
+      "presentation": "chip"
+    },
+    {
+      "name": "three_lf_lines",
+      "parts": [{ "value": "alpha\nbeta\ngamma", "repeat": 1 }],
+      "char_count": 16,
+      "logical_line_count": 3,
+      "presentation": "text"
+    },
+    {
+      "name": "four_lf_lines",
+      "parts": [{ "value": "a\nb\nc\nd", "repeat": 1 }],
+      "char_count": 7,
+      "logical_line_count": 4,
+      "presentation": "chip"
+    },
+    {
+      "name": "three_crlf_lines",
+      "parts": [{ "value": "a\r\nb\r\nc", "repeat": 1 }],
+      "char_count": 7,
+      "logical_line_count": 3,
+      "presentation": "text"
+    },
+    {
+      "name": "mixed_line_endings",
+      "parts": [{ "value": "a\r\nb\rc\nd", "repeat": 1 }],
+      "char_count": 8,
+      "logical_line_count": 4,
+      "presentation": "chip"
+    },
+    {
+      "name": "trailing_newline",
+      "parts": [{ "value": "a\n", "repeat": 1 }],
+      "char_count": 2,
+      "logical_line_count": 2,
+      "presentation": "text"
+    },
+    {
+      "name": "whitespace_rich_50",
+      "parts": [{ "value": " \t", "repeat": 25 }],
+      "char_count": 50,
+      "logical_line_count": 1,
+      "presentation": "text"
+    }
+  ]
+}

web/workspace/deno.json

@@ -6,7 +6,7 @@
     "dev": "deno run -A npm:vite@7.2.7 dev",
     "dev:backend": "cd ../.. && cargo run -p yoi-workspace-server --bin yoi-server -- serve --listen 127.0.0.1:8787",
     "check": "deno run -A npm:@sveltejs/kit@2.49.4 sync && deno run -A npm:svelte-check@4.3.4 --tsconfig ./tsconfig.json",
-    "test": "deno test --allow-read=src,test,tests --allow-env=LOG,VSCODE_TEXTMATE_DEBUG,NODE_ENV tests/workspace-model.test.ts tests/workspace-catalog.test.ts src/lib/workspace/auth/model.test.ts src/lib/workspace/api/http.test.ts src/lib/workspace/header/breadcrumb-model.test.ts src/lib/workspace/console/chat-submit.test.ts src/lib/workspace/console/composer-command.test.ts src/lib/workspace/console/composer-completion.test.ts src/lib/workspace/console/markdown.test.ts test/console/ansi.test.ts src/lib/workspace/console/model.test.ts src/lib/workspace/companion/api.test.ts tests/workdir-api.test.ts src/lib/workspace/console/tasks.test.ts test/ticket-detail-route-reuse.test.ts test/repositories/ui.test.ts src/lib/workspace/console/worker-console.ui.test.ts src/lib/workspace/settings/model.test.ts src/lib/workspace/sidebar/override-stack.test.ts src/lib/workspace/sidebar/workers.test.ts src/lib/workspace/sidebar/workspace-switcher.test.ts src/lib/workspace/sidebar/worker-subscription.test.ts src/lib/workspace/sidebar/worker-launch.test.ts src/lib/workspace/tickets/merge-request-resources.test.ts src/lib/workspace/tickets/ticket-panel.test.ts test/merge-request-status.test.ts test/config-source/decodal-grammar.test.ts test/config-source/editor-state.test.ts test/config-source/fixed-schema-wrapper.test.ts test/config-source/toolchain.test.ts test/config-source/wasm-parity.test.ts test/repository-access/api.test.ts test/repository-access/loader.test.ts test/repository-access/ui.test.ts",
+    "test": "deno test --allow-read=src,test,tests --allow-env=LOG,VSCODE_TEXTMATE_DEBUG,NODE_ENV tests/workspace-model.test.ts tests/workspace-catalog.test.ts src/lib/workspace/auth/model.test.ts src/lib/workspace/api/http.test.ts src/lib/workspace/header/breadcrumb-model.test.ts src/lib/workspace/console/chat-submit.test.ts tests/composer-paste.test.ts src/lib/workspace/console/composer-command.test.ts src/lib/workspace/console/composer-draft.test.ts src/lib/workspace/console/composer-completion.test.ts src/lib/workspace/console/markdown.test.ts test/console/ansi.test.ts src/lib/workspace/console/model.test.ts src/lib/workspace/companion/api.test.ts tests/workdir-api.test.ts src/lib/workspace/console/tasks.test.ts test/ticket-detail-route-reuse.test.ts test/repositories/ui.test.ts src/lib/workspace/console/worker-console.ui.test.ts src/lib/workspace/settings/model.test.ts src/lib/workspace/sidebar/override-stack.test.ts src/lib/workspace/sidebar/workers.test.ts src/lib/workspace/sidebar/workspace-switcher.test.ts src/lib/workspace/sidebar/worker-subscription.test.ts src/lib/workspace/sidebar/worker-launch.test.ts src/lib/workspace/tickets/merge-request-resources.test.ts src/lib/workspace/tickets/ticket-panel.test.ts test/merge-request-status.test.ts test/config-source/decodal-grammar.test.ts test/config-source/editor-state.test.ts test/config-source/fixed-schema-wrapper.test.ts test/config-source/toolchain.test.ts test/config-source/wasm-parity.test.ts test/repository-access/api.test.ts test/repository-access/loader.test.ts test/repository-access/ui.test.ts",
     "build": "deno run -A npm:vite@7.2.7 build",
     "preview": "deno run -A npm:vite@7.2.7 preview"
   },
@@ -16,6 +16,7 @@
     "@sveltejs/kit": "npm:@sveltejs/kit@2.49.4",
     "@sveltejs/vite-plugin-svelte": "npm:@sveltejs/vite-plugin-svelte@6.2.1",
     "@codemirror/autocomplete": "npm:@codemirror/autocomplete@6.20.0",
+    "@codemirror/commands": "npm:@codemirror/commands@6.9.0",
     "@codemirror/language": "npm:@codemirror/language@6.12.4",
     "@codemirror/state": "npm:@codemirror/state@6.7.1",
     "@codemirror/view": "npm:@codemirror/view@6.43.8",

web/workspace/deno.lock

@@ -4,6 +4,7 @@
     "jsr:@std/assert@*": "1.0.19",
     "jsr:@std/internal@^1.0.12": "1.0.14",
     "npm:@codemirror/autocomplete@6.20.0": "6.20.0",
+    "npm:@codemirror/commands@6.9.0": "6.9.0",
     "npm:@codemirror/language@6.12.4": "6.12.4",
     "npm:@codemirror/state@6.7.1": "6.7.1",
     "npm:@codemirror/view@6.43.8": "6.43.8",
@@ -47,6 +48,15 @@
         "@lezer/common"
       ]
     },
+    "@codemirror/commands@6.9.0": {
+      "integrity": "sha512-454TVgjhO6cMufsyyGN70rGIfJxJEjcqjBG2x2Y03Y/+Fm99d3O/Kv1QDYWuG6hvxsgmjXmBuATikIIYvERX+w==",
+      "dependencies": [
+        "@codemirror/language",
+        "@codemirror/state",
+        "@codemirror/view",
+        "@lezer/common"
+      ]
+    },
     "@codemirror/language@6.12.4": {
       "integrity": "sha512-1q4PaT+o6PbgpkJt4Q8Fv5XJxTy4FUZ4MWETtyiDw3J0Pyr9E2vqcKL+k9wcvjNTIsauxvE7OfmWj3FRPHQ76A==",
       "dependencies": [
@@ -1012,6 +1022,7 @@
   "workspace": {
     "dependencies": [
       "npm:@codemirror/autocomplete@6.20.0",
+      "npm:@codemirror/commands@6.9.0",
       "npm:@codemirror/language@6.12.4",
       "npm:@codemirror/state@6.7.1",
       "npm:@codemirror/view@6.43.8",

web/workspace/src/lib/generated/protocol.ts

@@ -133,7 +133,18 @@ message: string,
  */
 timestamp_ms: number, };
 
-export type Segment = { "kind": "text", content: string, } | { "kind": "paste", id: number, chars: number, lines: number, content: string, } | { "kind": "file_ref", path: string, } | { "kind": "flow", selector: string, } | { "kind": "unknown" };
+export type PasteArtifactMediaType = "text_plain_utf8";
+
+export type PasteArtifactAvailability = "available" | "unavailable" | "integrity_failed";
+
+export type PasteArtifactRef = { artifact_id: string, created_at_ms: number, media_type: PasteArtifactMediaType,
+/**
+ * Availability observed when this immutable reference was committed.
+ * Reads revalidate storage and integrity rather than trusting this field.
+ */
+availability: PasteArtifactAvailability, byte_len: number, char_count: number, line_count: number, sha256: string, source_entry_id: string, };
+
+export type Segment = { "kind": "text", content: string, } | { "kind": "paste", id: number, chars: number, lines: number, content: string, } | { "kind": "paste_artifact", artifact: PasteArtifactRef, } | { "kind": "file_ref", path: string, } | { "kind": "flow", selector: string, } | { "kind": "unknown" };
 
 export type WorkerEvent = { "kind": "turn_ended", worker_name: string, } | { "kind": "errored", worker_name: string, message: string, } | { "kind": "shut_down", worker_name: string, } | { "kind": "scope_sub_delegated",
 /**

web/workspace/src/lib/workspace/console/ComposerInput.svelte

@@ -0,0 +1,527 @@
+<script lang="ts">
+  import {
+    Compartment,
+    EditorSelection,
+    EditorState,
+    Prec,
+    StateEffect,
+    StateField,
+  } from "@codemirror/state";
+  import {
+    Decoration,
+    EditorView,
+    keymap,
+    WidgetType,
+    type DecorationSet,
+  } from "@codemirror/view";
+  import {
+    defaultKeymap,
+    history,
+    historyKeymap,
+    invertedEffects,
+    isolateHistory,
+  } from "@codemirror/commands";
+  import { onMount } from "svelte";
+  import type { Segment } from "$lib/generated/protocol.ts";
+  import {
+    measureComposerPaste,
+    type ComposerPasteMeasurement,
+  } from "$lib/workspace/console/composer-paste.ts";
+  import {
+    composerDeletionRange,
+    composerPasteAtoms,
+    composerPasteToken,
+    pasteChipLabel,
+    snapshotComposerDraft,
+    type ComposerDraftSnapshot,
+    type ComposerPaste,
+    type ComposerTextPaste,
+  } from "$lib/workspace/console/composer-draft.ts";
+  import { shouldSubmitChatKey } from "$lib/workspace/console/chat-submit.ts";
+
+  interface Props {
+    disabled?: boolean;
+    ariaLabel?: string;
+    ariaKeyShortcuts?: string;
+    onchange?: (snapshot: ComposerDraftSnapshot) => void;
+    onkeydown?: (event: KeyboardEvent) => void;
+    onsubmit?: () => void;
+  }
+
+  let {
+    disabled = false,
+    ariaLabel = "Message",
+    ariaKeyShortcuts = "Meta+Enter Control+Enter",
+    onchange,
+    onkeydown,
+    onsubmit,
+  }: Props = $props();
+
+  let mountElement: HTMLDivElement;
+  let view: EditorView | null = null;
+  let nextPasteId = 1;
+  let nextPasteKey = 1;
+  const editable = new Compartment();
+
+  const registerPaste = StateEffect.define<{ key: number; paste: ComposerPaste }>();
+  const pasteRegistry = StateField.define<ReadonlyMap<number, ComposerPaste>>({
+    create: () => new Map(),
+    update(registry, transaction) {
+      const additions = transaction.effects.filter((effect) => effect.is(registerPaste));
+      if (additions.length === 0) return registry;
+      const next = new Map(registry);
+      for (const addition of additions) {
+        next.set(addition.value.key, addition.value.paste);
+      }
+      return next;
+    },
+  });
+
+  const registerTextPaste = StateEffect.define<ComposerTextPaste>();
+  const restoreTextPastes = StateEffect.define<readonly ComposerTextPaste[]>();
+  const textPasteState = StateField.define<readonly ComposerTextPaste[]>({
+    create: () => [],
+    update(textPastes, transaction) {
+      const restored = transaction.effects.find((effect) =>
+        effect.is(restoreTextPastes)
+      );
+      if (restored) return restored.value;
+      const retained: ComposerTextPaste[] = [];
+      for (const paste of textPastes) {
+        let touched = false;
+        transaction.changes.iterChangedRanges((from, to) => {
+          const replacesContent = from < paste.to && to > paste.from;
+          const insertsInside = from === to && from > paste.from && from < paste.to;
+          if (replacesContent || insertsInside) touched = true;
+        });
+        if (touched) continue;
+        retained.push({
+          ...paste,
+          from: transaction.changes.mapPos(paste.from, 1),
+          to: transaction.changes.mapPos(paste.to, -1),
+        });
+      }
+      for (const effect of transaction.effects) {
+        if (effect.is(registerTextPaste)) retained.push(effect.value);
+      }
+      return retained;
+    },
+  });
+
+  class PasteChipWidget extends WidgetType {
+    readonly paste: ComposerPaste;
+
+    constructor(paste: ComposerPaste) {
+      super();
+      this.paste = paste;
+    }
+
+    override eq(other: PasteChipWidget): boolean {
+      return other.paste.id === this.paste.id &&
+        other.paste.content === this.paste.content &&
+        other.paste.chars === this.paste.chars &&
+        other.paste.lines === this.paste.lines;
+    }
+
+    override toDOM(): HTMLElement {
+      const chip = document.createElement("span");
+      const label = pasteChipLabel(this.paste);
+      chip.className = "composer-paste-chip";
+      chip.textContent = label;
+      chip.title = label;
+      chip.setAttribute("role", "note");
+      chip.setAttribute("aria-label", label);
+      return chip;
+    }
+
+    override ignoreEvent(): boolean {
+      return false;
+    }
+  }
+
+  function pasteDecorations(state: EditorState): DecorationSet {
+    const registry = state.field(pasteRegistry);
+    return Decoration.set(
+      composerPasteAtoms(state.doc.toString(), registry).map((paste) =>
+        Decoration.replace({
+          widget: new PasteChipWidget(paste),
+          inclusive: false,
+        }).range(paste.from, paste.to)
+      ),
+      true,
+    );
+  }
+
+  const pasteChips = [
+    pasteRegistry,
+    textPasteState,
+    invertedEffects.of((transaction) =>
+      transaction.docChanged
+        ? [restoreTextPastes.of(transaction.startState.field(textPasteState))]
+        : []
+    ),
+    EditorView.decorations.of((currentView) => pasteDecorations(currentView.state)),
+    EditorView.atomicRanges.of((currentView) => pasteDecorations(currentView.state)),
+  ];
+
+  function currentSnapshot(state = view?.state): ComposerDraftSnapshot {
+    if (!state) {
+      return { document: "", content: "", segments: [], pastes: [], textPastes: [] };
+    }
+    return snapshotComposerDraft(
+      state.doc.toString(),
+      state.field(pasteRegistry),
+      state.field(textPasteState),
+    );
+  }
+
+  function emitChange(): void {
+    onchange?.(currentSnapshot());
+  }
+
+  function insertPasteChip(content: string, measurement: ComposerPasteMeasurement): void {
+    if (!view) return;
+    const selection = view.state.selection.main;
+    const key = nextPasteKey++;
+    const paste: ComposerPaste = {
+      id: nextPasteId++,
+      content,
+      chars: measurement.charCount,
+      lines: measurement.logicalLineCount,
+    };
+    const token = composerPasteToken(key);
+    view.dispatch({
+      changes: { from: selection.from, to: selection.to, insert: token },
+      selection: EditorSelection.cursor(selection.from + token.length),
+      effects: registerPaste.of({ key, paste }),
+      annotations: isolateHistory.of("full"),
+      userEvent: "input.paste",
+    });
+  }
+
+  function insertTextPaste(content: string): void {
+    if (!view) return;
+    const selection = view.state.selection.main;
+    const rendered = view.state.toText(content).toString();
+    view.dispatch({
+      changes: { from: selection.from, to: selection.to, insert: rendered },
+      selection: EditorSelection.cursor(selection.from + rendered.length),
+      effects: registerTextPaste.of({
+        from: selection.from,
+        to: selection.from + rendered.length,
+        rendered,
+        content,
+      }),
+      annotations: isolateHistory.of("full"),
+      userEvent: "input.paste",
+    });
+  }
+
+  function handlePasteEvent(event: ClipboardEvent): boolean {
+    if (disabled || view?.state.readOnly) return false;
+    const content = event.clipboardData?.getData("text/plain");
+    if (!content) return false;
+    const measurement = measureComposerPaste(content);
+    event.preventDefault();
+    if (measurement.presentation === "chip") {
+      insertPasteChip(content, measurement);
+    } else {
+      insertTextPaste(content);
+    }
+    return true;
+  }
+
+  function selectedClipboardContent(state: EditorState): string | null {
+    const selection = state.selection.main;
+    if (selection.empty) return null;
+    const document = state.doc.sliceString(selection.from, selection.to);
+    const registry = state.field(pasteRegistry);
+    const selectedRegistry = new Map<number, ComposerPaste>();
+    for (const atom of composerPasteAtoms(state.doc.toString(), registry)) {
+      if (atom.from >= selection.from && atom.to <= selection.to) {
+        selectedRegistry.set(atom.key, atom);
+      }
+    }
+    const selectedTextPastes = state.field(textPasteState)
+      .filter((paste) => paste.from >= selection.from && paste.to <= selection.to)
+      .map((paste) => ({
+        ...paste,
+        from: paste.from - selection.from,
+        to: paste.to - selection.from,
+      }));
+    return snapshotComposerDraft(document, selectedRegistry, selectedTextPastes).content;
+  }
+
+  function deleteAdjacentPasteFromView(
+    currentView: EditorView,
+    direction: "backward" | "forward",
+  ): boolean {
+    if (currentView.state.readOnly) return false;
+    const selection = currentView.state.selection.main;
+    const pastes = composerPasteAtoms(
+      currentView.state.doc.toString(),
+      currentView.state.field(pasteRegistry),
+    );
+    const deletion = composerDeletionRange(selection, pastes, direction);
+    if (!deletion) return false;
+    currentView.dispatch({
+      changes: deletion,
+      selection: EditorSelection.cursor(deletion.from),
+      annotations: isolateHistory.of("full"),
+      userEvent: "delete",
+    });
+    return true;
+  }
+
+  onMount(() => {
+    view = new EditorView({
+      parent: mountElement,
+      state: EditorState.create({
+        extensions: [
+          history(),
+          Prec.highest(keymap.of([
+            {
+              key: "Mod-z",
+              run: (currentView) => currentView.state.readOnly,
+            },
+            {
+              key: "Mod-Shift-z",
+              run: (currentView) => currentView.state.readOnly,
+            },
+            {
+              key: "Mod-y",
+              run: (currentView) => currentView.state.readOnly,
+            },
+            {
+              key: "Backspace",
+              run: (currentView) =>
+                deleteAdjacentPasteFromView(currentView, "backward"),
+            },
+            {
+              key: "Delete",
+              run: (currentView) =>
+                deleteAdjacentPasteFromView(currentView, "forward"),
+            },
+          ])),
+          keymap.of([...defaultKeymap, ...historyKeymap]),
+          pasteChips,
+          editable.of([
+            EditorView.editable.of(!disabled),
+            EditorState.readOnly.of(disabled),
+          ]),
+          EditorState.allowMultipleSelections.of(false),
+          EditorView.lineWrapping,
+          EditorView.contentAttributes.of({
+            "aria-label": ariaLabel,
+            "aria-keyshortcuts": ariaKeyShortcuts,
+            "aria-multiline": "true",
+            role: "textbox",
+            spellcheck: "true",
+          }),
+          EditorView.updateListener.of((update) => {
+            if (update.docChanged || update.transactions.some((tx) => tx.effects.length > 0)) {
+              emitChange();
+            }
+          }),
+          Prec.high(EditorView.domEventHandlers({
+            paste(event) {
+              return handlePasteEvent(event);
+            },
+            copy(event, currentView) {
+              const content = selectedClipboardContent(currentView.state);
+              if (content === null || !event.clipboardData) return false;
+              event.preventDefault();
+              event.clipboardData.setData("text/plain", content);
+              return true;
+            },
+            cut(event, currentView) {
+              if (disabled) return false;
+              const content = selectedClipboardContent(currentView.state);
+              if (content === null || !event.clipboardData) return false;
+              event.preventDefault();
+              event.clipboardData.setData("text/plain", content);
+              const selection = currentView.state.selection.main;
+              currentView.dispatch({
+                changes: { from: selection.from, to: selection.to },
+                selection: EditorSelection.cursor(selection.from),
+                userEvent: "delete.cut",
+              });
+              return true;
+            },
+            keydown(event) {
+              onkeydown?.(event);
+              if (event.defaultPrevented) return true;
+              if (
+                shouldSubmitChatKey(event, {
+                  mode: "mod-enter",
+                  modKey: "auto",
+                  enabled: !disabled,
+                })
+              ) {
+                event.preventDefault();
+                onsubmit?.();
+                return true;
+              }
+              return false;
+            },
+          })),
+          EditorView.theme({
+            "&": { backgroundColor: "transparent" },
+            ".cm-scroller": { fontFamily: "inherit" },
+            ".cm-content": { caretColor: "var(--text-strong)" },
+            "&.cm-focused": { outline: "none" },
+          }),
+        ],
+      }),
+    });
+    emitChange();
+
+    return () => {
+      view?.destroy();
+      view = null;
+    };
+  });
+
+  $effect(() => {
+    const isDisabled = disabled;
+    view?.dispatch({
+      effects: editable.reconfigure([
+        EditorView.editable.of(!isDisabled),
+        EditorState.readOnly.of(isDisabled),
+      ]),
+    });
+  });
+
+  export function snapshot(): ComposerDraftSnapshot {
+    return currentSnapshot();
+  }
+
+  export function focus(): void {
+    view?.focus();
+  }
+
+  export function containsTarget(target: EventTarget | null): boolean {
+    return target instanceof Node && Boolean(view?.dom.contains(target));
+  }
+
+  export function cursor(): number {
+    return view?.state.selection.main.head ?? 0;
+  }
+
+  export function replaceRange(from: number, to: number, content: string): void {
+    if (!view || view.state.readOnly) return;
+    view.dispatch({
+      changes: { from, to, insert: content },
+      selection: EditorSelection.cursor(from + content.length),
+      userEvent: "input.complete",
+    });
+  }
+
+  export function clear(): void {
+    if (!view) return;
+    view.dispatch({
+      changes: { from: 0, to: view.state.doc.length, insert: "" },
+      selection: EditorSelection.cursor(0),
+      userEvent: "input",
+    });
+  }
+
+  export function restoreSegments(
+    segments: readonly Segment[],
+    preserveExactText = false,
+  ): void {
+    if (!view) return;
+    let document = "";
+    const pasteEffects: StateEffect<{ key: number; paste: ComposerPaste }>[] = [];
+    const textEffects: StateEffect<ComposerTextPaste>[] = [];
+    let highestPasteId = nextPasteId - 1;
+    for (const segment of segments) {
+      if (segment.kind === "text") {
+        const rendered = view.state.toText(segment.content).toString();
+        const from = document.length;
+        document += rendered;
+        if (preserveExactText) {
+          textEffects.push(registerTextPaste.of({
+            from,
+            to: from + rendered.length,
+            rendered,
+            content: segment.content,
+          }));
+        }
+      } else if (segment.kind === "paste") {
+        const key = nextPasteKey++;
+        const paste: ComposerPaste = {
+          id: segment.id,
+          content: segment.content,
+          chars: segment.chars,
+          lines: segment.lines,
+        };
+        highestPasteId = Math.max(highestPasteId, paste.id);
+        document += composerPasteToken(key);
+        pasteEffects.push(registerPaste.of({ key, paste }));
+      } else if (segment.kind === "file_ref") {
+        document += `@${segment.path}`;
+      }
+    }
+    nextPasteId = highestPasteId + 1;
+    view.dispatch({
+      changes: { from: 0, to: view.state.doc.length, insert: document },
+      selection: EditorSelection.cursor(document.length),
+      effects: [...pasteEffects, ...textEffects],
+      userEvent: "input.restore",
+    });
+  }
+</script>
+
+<div class="composer-input" class:disabled bind:this={mountElement}></div>
+
+<style>
+  .composer-input {
+    min-width: 0;
+    flex: 1;
+    color: var(--text-strong);
+    font: inherit;
+  }
+
+  .composer-input.disabled {
+    opacity: 0.56;
+  }
+
+  .composer-input :global(.cm-editor) {
+    min-height: 5.35rem;
+    max-height: 10rem;
+  }
+
+  .composer-input :global(.cm-scroller) {
+    overflow-y: auto;
+  }
+
+  .composer-input :global(.cm-content) {
+    min-height: 5.35rem;
+    padding: 0.55rem 3.4rem 3rem 0.65rem;
+    line-height: 1.45;
+  }
+
+  .composer-input :global(.cm-line) {
+    padding: 0;
+  }
+
+  .composer-input :global(.composer-paste-chip) {
+    display: inline-flex;
+    align-items: center;
+    max-width: min(26rem, 70vw);
+    margin: 0 0.15rem;
+    padding: 0.08rem 0.42rem;
+    overflow: hidden;
+    border: 1px solid color-mix(in srgb, var(--accent) 42%, var(--line));
+    border-radius: 999px;
+    background: color-mix(in srgb, var(--accent) 10%, var(--bg-subtle));
+    color: var(--text-muted);
+    font-size: 0.72rem;
+    font-weight: 600;
+    line-height: 1.35;
+    text-overflow: ellipsis;
+    vertical-align: baseline;
+    white-space: nowrap;
+  }
+</style>

web/workspace/src/lib/workspace/console/composer-command.ts

@@ -80,6 +80,85 @@ export function buildComposerRequest(value: string): ComposerCommandResult {
   };
 }
 
+export interface ComposerSegmentsRequestOptions {
+  preserveExactText?: boolean;
+}
+
+export function buildComposerSegmentsRequest(
+  sourceSegments: readonly Segment[],
+  options: ComposerSegmentsRequestOptions = {},
+): ComposerCommandResult {
+  const hasPaste = sourceSegments.some((segment) => segment.kind === "paste");
+  if (!hasPaste) {
+    const content = sourceSegments.map(segmentContent).join("");
+    if (!options.preserveExactText || content.trimStart().startsWith(":")) {
+      return buildComposerRequest(content);
+    }
+    if (!content.trim()) {
+      return { ok: false, message: "Input is empty." };
+    }
+    const segments = coalesceTextSegments(
+      sourceSegments.flatMap((segment) =>
+        segment.kind === "text"
+          ? parseSigilSegments(segment.content)
+          : [segment]
+      ),
+    );
+    return {
+      ok: true,
+      request: { kind: "user", content, segments },
+    };
+  }
+
+  const content = sourceSegments.map(segmentContent).join("");
+  if (!content.trim()) {
+    return { ok: false, message: "Input is empty." };
+  }
+  const leadingText = sourceSegments[0]?.kind === "text"
+    ? sourceSegments[0].content
+    : "";
+  if (leadingText.trimStart().startsWith(":")) {
+    return {
+      ok: false,
+      message:
+        "Commands cannot include a paste chip. Remove the chip or send it as a message.",
+    };
+  }
+
+  const segments: Segment[] = [];
+  for (const segment of sourceSegments) {
+    if (segment.kind === "text") {
+      segments.push(...parseSigilSegments(segment.content));
+    } else {
+      segments.push(segment);
+    }
+  }
+  return {
+    ok: true,
+    request: {
+      kind: "user",
+      content,
+      segments: coalesceTextSegments(segments),
+    },
+  };
+}
+
+function segmentContent(segment: Segment): string {
+  switch (segment.kind) {
+    case "text":
+    case "paste":
+      return segment.content;
+    case "file_ref":
+      return `@${segment.path}`;
+    case "flow":
+      return segment.selector;
+    case "paste_artifact":
+      return "";
+    default:
+      return "";
+  }
+}
+
 function buildColonCommand(commandLine: string): ComposerCommandResult {
   const [name = "", ...argv] = commandLine.trim().split(/\s+/).filter(Boolean);
   if (!name) {

web/workspace/src/lib/workspace/console/composer-draft.test.ts

@@ -0,0 +1,235 @@
+import type { Segment } from "$lib/generated/protocol.ts";
+import {
+  composerDeletionRange,
+  type ComposerPaste,
+  composerPasteToken,
+  pasteChipLabel,
+  snapshotComposerDraft,
+} from "$lib/workspace/console/composer-draft.ts";
+import { buildComposerSegmentsRequest } from "$lib/workspace/console/composer-command.ts";
+import { measureComposerPaste } from "$lib/workspace/console/composer-paste.ts";
+
+declare const Deno: {
+  test(name: string, fn: () => void): void;
+};
+
+function assert(
+  condition: unknown,
+  message = "assertion failed",
+): asserts condition {
+  if (!condition) throw new Error(message);
+}
+
+function assertEquals(actual: unknown, expected: unknown): void {
+  const actualJson = JSON.stringify(actual);
+  const expectedJson = JSON.stringify(expected);
+  if (actualJson !== expectedJson) {
+    throw new Error(`expected ${expectedJson}, received ${actualJson}`);
+  }
+}
+
+function paste(id: number, content: string): ComposerPaste {
+  const measurement = measureComposerPaste(content);
+  return {
+    id,
+    content,
+    chars: measurement.charCount,
+    lines: measurement.logicalLineCount,
+  };
+}
+
+Deno.test("composer draft preserves mixed Text and Paste order exactly", () => {
+  const unicodeCrlf = "🙂界\r\nsecond\r\n";
+  const trailingNewline = `${"x".repeat(51)}\n`;
+  const registry = new Map<number, ComposerPaste>([
+    [11, paste(1, unicodeCrlf)],
+    [12, paste(2, trailingNewline)],
+  ]);
+  const document = `before ${composerPasteToken(11)} middle ${
+    composerPasteToken(12)
+  } after`;
+
+  const snapshot = snapshotComposerDraft(document, registry);
+
+  assertEquals(
+    snapshot.content,
+    `before ${unicodeCrlf} middle ${trailingNewline} after`,
+  );
+  assertEquals(snapshot.segments, [
+    { kind: "text", content: "before " },
+    {
+      kind: "paste",
+      id: 1,
+      content: unicodeCrlf,
+      chars: 12,
+      lines: 3,
+    },
+    { kind: "text", content: " middle " },
+    {
+      kind: "paste",
+      id: 2,
+      content: trailingNewline,
+      chars: 52,
+      lines: 2,
+    },
+    { kind: "text", content: " after" },
+  ]);
+  assertEquals(snapshot.pastes.map((entry) => entry.key), [11, 12]);
+});
+
+Deno.test("selection deletion covers mixed Text and every selected paste chip", () => {
+  const pastes = [
+    { ...paste(1, "first"), key: 10, from: 2, to: 5 },
+    { ...paste(2, "second"), key: 11, from: 8, to: 11 },
+  ];
+
+  assertEquals(
+    composerDeletionRange({ from: 1, to: 12, head: 12 }, pastes, "backward"),
+    { from: 1, to: 12 },
+  );
+  assertEquals(
+    composerDeletionRange({ from: 2, to: 11, head: 2 }, pastes, "forward"),
+    { from: 2, to: 11 },
+  );
+  assertEquals(
+    composerDeletionRange({ from: 5, to: 5, head: 5 }, pastes, "backward"),
+    { from: 2, to: 5 },
+  );
+  assertEquals(
+    composerDeletionRange({ from: 8, to: 8, head: 8 }, pastes, "forward"),
+    { from: 8, to: 11 },
+  );
+});
+
+Deno.test("composer paste chip label is compact and accessible", () => {
+  assertEquals(
+    pasteChipLabel({ id: 4, content: "payload", chars: 7, lines: 1 }),
+    "Clipboard #4 · 7 chars · 1 line",
+  );
+});
+
+Deno.test("typed composer restoration retains Paste ids and metadata", () => {
+  const original: Segment[] = [
+    { kind: "text", content: "prefix\n" },
+    {
+      kind: "paste",
+      id: 9,
+      content: "alpha\r\nbeta\r\n",
+      chars: 13,
+      lines: 3,
+    },
+    { kind: "text", content: "\nsuffix" },
+  ];
+  const registry = new Map<number, ComposerPaste>([
+    [31, original[1] as Extract<Segment, { kind: "paste" }>],
+  ]);
+  const restored = snapshotComposerDraft(
+    `prefix\n${composerPasteToken(31)}\nsuffix`,
+    registry,
+  );
+
+  assertEquals(restored.segments, original);
+});
+
+Deno.test("mixed composer request preserves Paste and parsed file-ref boundaries", () => {
+  const segments: Segment[] = [
+    { kind: "text", content: "inspect @src/main.rs then " },
+    {
+      kind: "paste",
+      id: 2,
+      content: "a\r\nb\r\n",
+      chars: 6,
+      lines: 3,
+    },
+    { kind: "text", content: " exactly" },
+  ];
+
+  const result = buildComposerSegmentsRequest(segments);
+  assert(result.ok);
+  assertEquals(result.request, {
+    kind: "user",
+    content: "inspect @src/main.rs then a\r\nb\r\n exactly",
+    segments: [
+      { kind: "text", content: "inspect " },
+      { kind: "file_ref", path: "src/main.rs" },
+      { kind: "text", content: " then " },
+      segments[1],
+      segments[2],
+    ],
+  });
+});
+
+Deno.test("short-paste Text preserves CRLF, trailing newline, and surrounding whitespace", () => {
+  const original = "  short\r\npaste\r\n  ";
+  const rendered = "  short\npaste\n  ";
+  const snapshot = snapshotComposerDraft(rendered, new Map(), [{
+    from: 0,
+    to: rendered.length,
+    rendered,
+    content: original,
+  }]);
+
+  assertEquals(snapshot.content, original);
+  assertEquals(snapshot.segments, [{ kind: "text", content: original }]);
+  assertEquals(snapshot.textPastes.length, 1);
+
+  const result = buildComposerSegmentsRequest(snapshot.segments, {
+    preserveExactText: snapshot.textPastes.length > 0,
+  });
+  assert(result.ok);
+  assertEquals(result.request, {
+    kind: "user",
+    content: original,
+    segments: [{ kind: "text", content: original }],
+  });
+});
+
+Deno.test("edited short-paste provenance falls back to visible Text", () => {
+  const snapshot = snapshotComposerDraft("changed", new Map(), [{
+    from: 0,
+    to: 5,
+    rendered: "short",
+    content: "short\r\n",
+  }]);
+
+  assertEquals(snapshot.content, "changed");
+  assertEquals(snapshot.segments, [{ kind: "text", content: "changed" }]);
+  assertEquals(snapshot.textPastes, []);
+});
+
+Deno.test("Paste content beginning with a colon remains opaque user input", () => {
+  const directPaste: Segment = {
+    kind: "paste",
+    id: 3,
+    content: ":not-a-command\r\n",
+    chars: 16,
+    lines: 2,
+  };
+  const direct = buildComposerSegmentsRequest([directPaste]);
+  assert(direct.ok);
+  assertEquals(direct.request, {
+    kind: "user",
+    content: ":not-a-command\r\n",
+    segments: [directPaste],
+  });
+
+  const afterWhitespace = buildComposerSegmentsRequest([
+    { kind: "text", content: "  " },
+    directPaste,
+  ]);
+  assert(afterWhitespace.ok);
+  assert(afterWhitespace.request);
+  assertEquals(afterWhitespace.request.kind, "user");
+  assertEquals(afterWhitespace.request.content, "  :not-a-command\r\n");
+});
+
+Deno.test("plain short-paste Text retains the existing composer request path", () => {
+  const result = buildComposerSegmentsRequest([
+    { kind: "text", content: "  short\r\npaste\r\n  " },
+  ]);
+  assert(result.ok);
+  assertEquals(result.request, {
+    kind: "user",
+    content: "short\r\npaste",
+  });
+});

web/workspace/src/lib/workspace/console/composer-draft.ts

@@ -0,0 +1,151 @@
+import type { Segment } from "$lib/generated/protocol.ts";
+
+const PASTE_TOKEN_PREFIX = "\uFFF9";
+const PASTE_TOKEN_SUFFIX = "\uFFFB";
+const PASTE_TOKEN_PATTERN = /\uFFF9(\d+)\uFFFB/g;
+
+export interface ComposerPaste {
+  id: number;
+  content: string;
+  chars: number;
+  lines: number;
+}
+
+export interface ComposerPasteAtom extends ComposerPaste {
+  key: number;
+  from: number;
+  to: number;
+}
+
+export interface ComposerTextPaste {
+  from: number;
+  to: number;
+  rendered: string;
+  content: string;
+}
+
+export interface ComposerSelection {
+  from: number;
+  to: number;
+  head: number;
+}
+
+export function composerDeletionRange(
+  selection: ComposerSelection,
+  pastes: readonly ComposerPasteAtom[],
+  direction: "backward" | "forward",
+): { from: number; to: number } | null {
+  if (selection.from !== selection.to) {
+    return { from: selection.from, to: selection.to };
+  }
+  const paste = direction === "backward"
+    ? pastes.find((candidate) => candidate.to === selection.head)
+    : pastes.find((candidate) => candidate.from === selection.head);
+  return paste ? { from: paste.from, to: paste.to } : null;
+}
+
+export interface ComposerDraftSnapshot {
+  document: string;
+  content: string;
+  segments: Segment[];
+  pastes: ComposerPasteAtom[];
+  textPastes: ComposerTextPaste[];
+}
+
+export function composerPasteToken(key: number): string {
+  return `${PASTE_TOKEN_PREFIX}${key}${PASTE_TOKEN_SUFFIX}`;
+}
+
+export function composerPasteAtoms(
+  document: string,
+  registry: ReadonlyMap<number, ComposerPaste>,
+): ComposerPasteAtom[] {
+  const atoms: ComposerPasteAtom[] = [];
+  for (const match of document.matchAll(PASTE_TOKEN_PATTERN)) {
+    const key = Number(match[1]);
+    const paste = registry.get(key);
+    if (!paste || match.index === undefined) continue;
+    atoms.push({
+      ...paste,
+      key,
+      from: match.index,
+      to: match.index + match[0].length,
+    });
+  }
+  return atoms;
+}
+
+function appendTextSegment(segments: Segment[], content: string): void {
+  if (content.length === 0) return;
+  const previous = segments.at(-1);
+  if (previous?.kind === "text") {
+    previous.content += content;
+  } else {
+    segments.push({ kind: "text", content });
+  }
+}
+
+export function snapshotComposerDraft(
+  document: string,
+  registry: ReadonlyMap<number, ComposerPaste>,
+  candidateTextPastes: readonly ComposerTextPaste[] = [],
+): ComposerDraftSnapshot {
+  const pastes = composerPasteAtoms(document, registry);
+  const textPastes = candidateTextPastes
+    .filter((paste) =>
+      paste.from >= 0 &&
+      paste.to <= document.length &&
+      document.slice(paste.from, paste.to) === paste.rendered
+    )
+    .sort((left, right) => left.from - right.from);
+  const events = [
+    ...pastes.map((paste) => ({
+      kind: "paste" as const,
+      from: paste.from,
+      to: paste.to,
+      paste,
+    })),
+    ...textPastes.map((paste) => ({
+      kind: "text_paste" as const,
+      from: paste.from,
+      to: paste.to,
+      paste,
+    })),
+  ].sort((left, right) => left.from - right.from);
+  const segments: Segment[] = [];
+  let content = "";
+  let cursor = 0;
+
+  for (const event of events) {
+    if (event.from < cursor) continue;
+    const text = document.slice(cursor, event.from);
+    appendTextSegment(segments, text);
+    content += text;
+
+    if (event.kind === "paste") {
+      segments.push({
+        kind: "paste",
+        id: event.paste.id,
+        content: event.paste.content,
+        chars: event.paste.chars,
+        lines: event.paste.lines,
+      });
+    } else {
+      appendTextSegment(segments, event.paste.content);
+    }
+    content += event.paste.content;
+    cursor = event.to;
+  }
+
+  const trailingText = document.slice(cursor);
+  appendTextSegment(segments, trailingText);
+  content += trailingText;
+
+  return { document, content, segments, pastes, textPastes };
+}
+
+export function pasteChipLabel(paste: ComposerPaste): string {
+  const chars = paste.chars === 1 ? "char" : "chars";
+  const lines = paste.lines === 1 ? "line" : "lines";
+  return `Clipboard #${paste.id} · ${paste.chars} ${chars} · ${paste.lines} ${lines}`;
+}

web/workspace/src/lib/workspace/console/composer-paste.ts

@@ -0,0 +1,87 @@
+export const MAX_PLAIN_TEXT_PASTE_CHARS = 50;
+export const MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES = 3;
+
+export type ComposerPastePresentation = "text" | "chip";
+
+export interface ComposerPasteMeasurement {
+  charCount: number;
+  logicalLineCount: number;
+  presentation: ComposerPastePresentation;
+}
+
+export interface ComposerPasteEvent {
+  clipboardData: { getData(format: string): string } | null;
+  preventDefault(): void;
+}
+
+/**
+ * Count user-visible Unicode scalar values rather than UTF-16 code units.
+ * JavaScript string iteration combines a valid surrogate pair into one value.
+ */
+export function unicodeScalarCount(content: string): number {
+  let count = 0;
+  for (const _value of content) count += 1;
+  return count;
+}
+
+/**
+ * Empty content has zero logical lines. Otherwise each LF, lone CR, or CRLF
+ * advances one line; CRLF is one break rather than two.
+ */
+export function logicalLineCount(content: string): number {
+  if (content.length === 0) return 0;
+
+  let count = 1;
+  for (let index = 0; index < content.length; index += 1) {
+    const codeUnit = content.charCodeAt(index);
+    if (codeUnit === 0x0d) {
+      if (content.charCodeAt(index + 1) === 0x0a) index += 1;
+      count += 1;
+    } else if (codeUnit === 0x0a) {
+      count += 1;
+    }
+  }
+  return count;
+}
+
+export function measureComposerPaste(
+  content: string,
+): ComposerPasteMeasurement {
+  const charCount = unicodeScalarCount(content);
+  const logicalLineCountValue = logicalLineCount(content);
+  const presentation = charCount <= MAX_PLAIN_TEXT_PASTE_CHARS &&
+      logicalLineCountValue <= MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES
+    ? "text"
+    : "chip";
+
+  return {
+    charCount,
+    logicalLineCount: logicalLineCountValue,
+    presentation,
+  };
+}
+
+/**
+ * Route a Browser paste without disrupting native short-text editing.
+ *
+ * Returning false means the caller must leave the event untouched, preserving
+ * the Browser's cursor, selection replacement, and undo behavior. A chip paste
+ * is consumed exactly once and handed to the compact-paste implementation.
+ */
+export function handleComposerPaste(
+  event: ComposerPasteEvent,
+  insertCompactPaste: (
+    content: string,
+    measurement: ComposerPasteMeasurement,
+  ) => void,
+): boolean {
+  if (!event.clipboardData) return false;
+
+  const content = event.clipboardData.getData("text/plain");
+  const measurement = measureComposerPaste(content);
+  if (measurement.presentation === "text") return false;
+
+  event.preventDefault();
+  insertCompactPaste(content, measurement);
+  return true;
+}

web/workspace/src/lib/workspace/console/model.test.ts

@@ -137,6 +137,30 @@ function snapshotEvent(cwd: string, entries: unknown[] = []): Event {
   };
 }
 
+Deno.test("large paste segments project compact artifact metadata", () => {
+  const body = "secret pasted body";
+  const text = segmentsToText([{
+    kind: "paste_artifact",
+    artifact: {
+      artifact_id: "019ca7c8-57b6-7f05-8edf-524147aba7b2",
+      created_at_ms: 1_700_000_000_000,
+      media_type: "text_plain_utf8",
+      availability: "available",
+      byte_len: 65536,
+      char_count: 65530,
+      line_count: 200,
+      sha256: "a".repeat(64),
+      source_entry_id: "entry-1",
+    },
+  }]);
+  assert(text.includes("019ca7c8-57b6-7f05-8edf-524147aba7b2"), "artifact id is visible");
+  assert(text.includes("65536 bytes"), "bounded size metadata is visible");
+  assert(text.includes("text_plain_utf8"), "media type is visible");
+  assert(text.includes("available"), "availability is visible");
+  assert(text.includes("1700000000000"), "creation time is visible");
+  assert(!text.includes(body), "artifact body is not projected");
+});
+
 Deno.test("console routing projects live errors but not completion replies", () => {
   const errorEvent = {
     event: "error",

web/workspace/src/lib/workspace/console/model.ts

@@ -1069,6 +1069,8 @@ export function segmentsToText(segments: Segment[]): string {
         case "paste":
           return segment.content ||
             `[paste ${segment.id}: ${segment.chars} chars / ${segment.lines} lines]`;
+        case "paste_artifact":
+          return `[Large paste artifact ${segment.artifact.artifact_id}: ${segment.artifact.byte_len} bytes, ${segment.artifact.media_type}, ${segment.artifact.availability}, created ${segment.artifact.created_at_ms} ms, sha256 ${segment.artifact.sha256}]`;
         case "file_ref":
           return `@file ${segment.path}`;
         case "unknown":

web/workspace/src/lib/workspace/console/worker-console.ui.test.ts

@@ -554,18 +554,22 @@ Deno.test("Worker Console removes redundant chrome and uses shared alerts", asyn
   );
 });
 
-Deno.test("Worker Console composer fits to content without manual resize", async () => {
+Deno.test("Worker Console composer keeps a compact bounded chip editor", async () => {
   const consolePage = await Deno.readTextFile(
     new URL(
       "./../../../routes/w/[workspaceId]/runtimes/[runtimeId]/workers/[workerId]/console/+page.svelte",
       import.meta.url,
     ),
   );
+  const composerInput = await Deno.readTextFile(
+    new URL("./ComposerInput.svelte", import.meta.url),
+  );
   assert(
-    consolePage.includes("use:fitTextarea={{ value: draft, maxRows: 10 }}") &&
+    consolePage.includes("<ComposerInput") &&
       consolePage.includes('<div class="composer-input-shell">') &&
       !consolePage.includes("handleComposerShellClick") &&
-      consolePage.includes("bind:this={composerTextareaElement}") &&
+      consolePage.includes("bind:this={composerInputElement}") &&
+      consolePage.includes("onchange={handleComposerChange}") &&
       consolePage.includes(
         'event.key === "PageUp" || event.key === "PageDown"',
       ) &&
@@ -577,10 +581,46 @@ Deno.test("Worker Console composer fits to content without manual resize", async
       consolePage.includes("pointer-events: auto") &&
       consolePage.includes('class="composer-send-icon"') &&
       consolePage.includes('d="M8 6L12 2L16 6"') &&
-      consolePage.includes(".console-composer textarea") &&
-      consolePage.includes("resize: none") &&
-      consolePage.includes("overflow-y: hidden"),
-    "Console composer should autosize to content, cap at ten rows, wrap input and icon send button, and disable manual resize",
+      composerInput.includes("max-height: 10rem") &&
+      composerInput.includes("EditorView.lineWrapping") &&
+      composerInput.includes("overflow-y: auto"),
+    "Console composer should use the bounded chip-capable editor with wrapping, page scrolling, and the icon send button",
+  );
+});
+
+Deno.test("Worker Console paste chips preserve typed draft and target authority", async () => {
+  const consolePage = await Deno.readTextFile(
+    new URL(
+      "./../../../routes/w/[workspaceId]/runtimes/[runtimeId]/workers/[workerId]/console/+page.svelte",
+      import.meta.url,
+    ),
+  );
+  const composerInput = await Deno.readTextFile(
+    new URL("./ComposerInput.svelte", import.meta.url),
+  );
+  assert(
+    composerInput.includes('measurement.presentation === "chip"') &&
+      composerInput.includes("registerTextPaste") &&
+      composerInput.includes("EditorView.atomicRanges") &&
+      composerInput.includes('key: "Backspace"') &&
+      composerInput.includes('key: "Delete"') &&
+      composerInput.includes(
+        "composerDeletionRange(selection, pastes, direction)",
+      ) &&
+      composerInput.includes("EditorState.readOnly.of(isDisabled)") &&
+      composerInput.includes('key: "Mod-z"') &&
+      composerInput.includes("if (!view || view.state.readOnly) return") &&
+      composerInput.includes("if (currentView.state.readOnly) return false") &&
+      consolePage.includes("activeComposerTargetKey !== targetKey") &&
+      consolePage.includes("if (!composerEditable) return") &&
+      composerInput.includes('chip.setAttribute("aria-label", label)') &&
+      composerInput.includes("preserveExactText = false") &&
+      consolePage.includes("buildComposerSegmentsRequest(value.segments, {") &&
+      consolePage.includes("preserveExactText: value.textPastes.length > 0") &&
+      consolePage.includes("composerDrafts.set(activeComposerTargetKey") &&
+      consolePage.includes("switchComposerTarget(target)") &&
+      consolePage.includes('sendControl({ method: "cancel" }, "Stop")'),
+    "Paste chips should use shared threshold classification, atomic keyboard behavior, accessible labels, typed restore, and per-Worker draft authority",
   );
 });
 
@@ -742,7 +782,7 @@ Deno.test("Worker Console page is routed by runtime_id and worker_id through bac
         'const composerEditable = $derived(protocolState === "open" && !sending);',
       ) &&
       consolePage.includes('sendControl({ method: "cancel" }, "Stop")') &&
-      consolePage.includes("enabled: canSubmitDraft") &&
+      consolePage.includes("onsubmit={handleComposerSubmit}") &&
       consolePage.includes("disabled={!composerEditable}") &&
       consolePage.includes("class:stop={workerRunning}") &&
       consolePage.includes('"Stop Worker"') &&

web/workspace/src/routes/w/[workspaceId]/runtimes/[runtimeId]/workers/[workerId]/console/+page.svelte

@@ -1,22 +1,21 @@
 <script lang="ts">
-    import { tick, untrack } from "svelte";
+    import { tick, untrack, type SvelteComponent } from "svelte";
     import ConsoleLineItem from "$lib/workspace/console/ConsoleLineItem.svelte";
     import ConsoleTasks from "$lib/workspace/console/ConsoleTasks.svelte";
     import ConsoleTimeline from "$lib/workspace/console/ConsoleTimeline.svelte";
-    import { chatSubmit } from "$lib/workspace/console/chat-submit";
+    import ComposerInput from "$lib/workspace/console/ComposerInput.svelte";
+    import type { ComposerDraftSnapshot } from "$lib/workspace/console/composer-draft";
     import {
-        buildComposerRequest,
+        buildComposerSegmentsRequest,
         type WorkerConsoleInputRequest,
     } from "$lib/workspace/console/composer-command";
     import {
-        applyCompletion,
         completionTokenAt,
         localCommandCompletions,
         type ComposerCompletionEntry,
         type ComposerCompletionToken,
     } from "$lib/workspace/console/composer-completion";
     import WorkerRunStatus from "$lib/workspace/console/WorkerRunStatus.svelte";
-    import { fitTextarea } from "$lib/workspace/console/textarea-fit";
     import { resolveWorkerControlShortcut } from "$lib/workspace/console/worker-control-shortcuts";
     import {
         consoleWorkerViews,
@@ -103,7 +102,33 @@
         untrack(() => data.worker?.state ?? null),
     );
     let workerError = $state<string | null>(untrack(() => data.workerError));
-    let draft = $state("");
+    type ComposerInputHandle = {
+        snapshot(): ComposerDraftSnapshot;
+        focus(): void;
+        containsTarget(target: EventTarget | null): boolean;
+        cursor(): number;
+        replaceRange(from: number, to: number, content: string): void;
+        clear(): void;
+        restoreSegments(
+            segments: readonly Segment[],
+            preserveExactText?: boolean,
+        ): void;
+    };
+
+    type ComposerDraftCache = {
+        segments: Segment[];
+        preserveExactText: boolean;
+    };
+
+    const EMPTY_DRAFT: ComposerDraftSnapshot = {
+        document: "",
+        content: "",
+        segments: [],
+        pastes: [],
+        textPastes: [],
+    };
+
+    let draft = $state<ComposerDraftSnapshot>(EMPTY_DRAFT);
     let completionEntries = $state<ComposerCompletionEntry[]>([]);
     let completionToken = $state<ComposerCompletionToken | null>(null);
     let completionBusy = $state(false);
@@ -130,7 +155,13 @@
     let timelineOpen = $state(false);
     let consoleViewMode = $state<ConsoleViewMode>("overview");
     let consoleBodyElement: HTMLElement | null = null;
-    let composerTextareaElement: HTMLTextAreaElement | null = null;
+    let composerInputElement = $state<
+        (SvelteComponent & ComposerInputHandle) | null
+    >(null);
+    const composerDrafts = new Map<string, ComposerDraftCache>();
+    let activeComposerTargetKey = untrack(
+        () => `${workspaceId}:${runtimeId}:${workerId}`,
+    );
     let timelineRailDragCleanup: (() => void) | null = null;
     let autoFollowConsole = $state(true);
     let consoleScroll = $state<ScrollMetrics>({ top: 0, height: 1, client: 1 });
@@ -196,7 +227,7 @@
     const inputReady = $derived(workerState === "idle");
     const composerEditable = $derived(protocolState === "open" && !sending);
     const canSubmitDraft = $derived(inputReady && composerEditable);
-    const canSend = $derived(canSubmitDraft && draft.trim().length > 0);
+    const canSend = $derived(canSubmitDraft && draft.content.trim().length > 0);
     const canStopFromComposer = $derived(workerRunning && composerEditable);
     const composerSubmitDisabled = $derived(
         workerRunning ? !canStopFromComposer : !canSend,
@@ -321,14 +352,14 @@
         scheduleObservationFlush();
     }
 
-    async function applyComposerCompletion(event: KeyboardEvent) {
-        const target = event.currentTarget;
-        if (!(target instanceof HTMLTextAreaElement)) {
-            return;
-        }
+    async function applyComposerCompletion() {
+        if (!composerEditable || !composerInputElement) return;
+        const input = composerInputElement;
+        const targetKey = activeComposerTargetKey;
+        const document = draft.document;
         const token = completionTokenAt(
-            draft,
-            target.selectionStart ?? draft.length,
+            document,
+            input.cursor(),
         );
         completionToken = token;
         completionError = null;
@@ -340,15 +371,24 @@
         completionBusy = true;
         try {
             const entries = await resolveCompletionEntries(token);
+            if (
+                !composerEditable ||
+                composerInputElement !== input ||
+                activeComposerTargetKey !== targetKey ||
+                draft.document !== document
+            ) {
+                return;
+            }
             completionEntries = entries;
             if (entries.length === 0) {
                 completionError = `No completions for ${token.sigil}${token.prefix}`;
                 return;
             }
-            const applied = applyCompletion(draft, token, entries[0]);
-            draft = applied.value;
-            await tick();
-            target.setSelectionRange(applied.cursor, applied.cursor);
+            input.replaceRange(
+                token.start,
+                token.end,
+                `${entries[0].value} `,
+            );
             composerNotice =
                 entries.length > 1
                     ? `Completed ${token.sigil}${entries[0].value}; ${entries.length - 1} more candidate(s)`
@@ -404,7 +444,8 @@
             return;
         }
         event.preventDefault();
-        void applyComposerCompletion(event);
+        if (!composerEditable) return;
+        void applyComposerCompletion();
     }
 
     function scrollConsoleByPage(direction: 1 | -1) {
@@ -465,13 +506,13 @@
     }
 
     function handleWorkerControlShortcut(event: KeyboardEvent) {
-        const composerFocused = event.target === composerTextareaElement;
+        const composerFocused = composerInputElement?.containsTarget(event.target) ?? false;
         const command = resolveWorkerControlShortcut(event, {
             protocolOpen: protocolState === "open",
             running: workerRunning,
             paused: workerPaused,
             composerFocused,
-            draftBlank: draft.trim().length === 0,
+            draftBlank: draft.content.trim().length === 0,
             editableTarget: isEditableTarget(event.target) && !composerFocused,
             hasSelection: targetHasSelection(event.target),
         });
@@ -529,16 +570,53 @@
         }
     }
 
-    function handleComposerSubmit(value = draft) {
+    function cachedComposerDraft(snapshot: ComposerDraftSnapshot): ComposerDraftCache {
+        return {
+            segments: [...snapshot.segments],
+            preserveExactText: snapshot.textPastes.length > 0,
+        };
+    }
+
+    function handleComposerChange(snapshot: ComposerDraftSnapshot) {
+        draft = snapshot;
+        composerDrafts.set(activeComposerTargetKey, cachedComposerDraft(snapshot));
+    }
+
+    function switchComposerTarget(target: ConsoleTarget) {
+        const nextKey = `${target.workspaceId}:${target.runtimeId}:${target.workerId}`;
+        if (nextKey === activeComposerTargetKey) return;
+        if (composerInputElement) {
+            composerDrafts.set(
+                activeComposerTargetKey,
+                cachedComposerDraft(composerInputElement.snapshot()),
+            );
+        }
+        activeComposerTargetKey = nextKey;
+        const restored = composerDrafts.get(nextKey) ?? {
+            segments: [],
+            preserveExactText: false,
+        };
+        void tick().then(() => {
+            if (activeComposerTargetKey !== nextKey) return;
+            composerInputElement?.restoreSegments(
+                restored.segments,
+                restored.preserveExactText,
+            );
+        });
+    }
+
+    function handleComposerSubmit() {
         if (workerRunning) {
             sendControl({ method: "cancel" }, "Stop");
             return;
         }
-        void submitDraft(value);
+        void submitDraft(composerInputElement?.snapshot() ?? draft);
     }
 
-    async function submitDraft(value = draft) {
-        const command = buildComposerRequest(value);
+    async function submitDraft(value: ComposerDraftSnapshot) {
+        const command = buildComposerSegmentsRequest(value.segments, {
+            preserveExactText: value.textPastes.length > 0,
+        });
         if (!command.ok) {
             composerNotice = null;
             sendError = command.message;
@@ -546,7 +624,7 @@
         }
         composerNotice = command.notice ?? null;
         if (!command.request) {
-            draft = "";
+            composerInputElement?.clear();
             return;
         }
         if (sending || !inputReady) {
@@ -558,7 +636,7 @@
         try {
             const method = composerRequestToProtocolMethod(command.request);
             sendProtocolMethod(method);
-            draft = "";
+            composerInputElement?.clear();
             if (method.method === "run" || method.method === "notify") {
                 liveWorkerState = "running";
             }
@@ -1242,6 +1320,7 @@
 
     $effect(() => {
         const target = consoleTarget;
+        switchComposerTarget(target);
         const targetWorker = data.worker;
         const targetWorkerError = data.workerError;
         workerViewSelectionGeneration += 1;
@@ -1521,19 +1600,15 @@
 
     <form class="console-composer" onsubmit={sendMessage}>
         <div class="composer-input-shell">
-            <textarea
-                id="worker-console-message"
-                aria-label="Console input"
-                aria-keyshortcuts="Meta+Enter Control+Enter"
-                bind:this={composerTextareaElement}
-                bind:value={draft}
-                use:chatSubmit={{
-                    enabled: canSubmitDraft,
-                    onSubmit: (value) => handleComposerSubmit(value),
-                }}
-                use:fitTextarea={{ value: draft, maxRows: 10 }}
+            <ComposerInput
+                bind:this={composerInputElement}
+                ariaLabel="Console input"
+                ariaKeyShortcuts="Meta+Enter Control+Enter"
+                disabled={!composerEditable}
+                onchange={handleComposerChange}
                 onkeydown={handleComposerKeydown}
-                disabled={!composerEditable}></textarea>
+                onsubmit={handleComposerSubmit}
+            />
             <div class="composer-input-footer">
                 <div class="composer-footer-slot">
                     {#if completionBusy || completionError || completionEntries.length > 0}
@@ -1875,27 +1950,6 @@
         min-width: 0;
     }
 
-    .console-composer textarea {
-        box-sizing: border-box;
-        width: 100%;
-        min-height: 5.35rem;
-        resize: none;
-        overflow-y: hidden;
-        border: 0;
-        border-radius: 14px;
-        background: transparent;
-        padding: 0.55rem 3.4rem 3rem 0.65rem;
-        font: inherit;
-        line-height: 1.45;
-        color: var(--text-strong);
-        outline: none;
-        cursor: text;
-    }
-
-    .console-composer textarea:disabled {
-        color: var(--text-muted);
-    }
-
     .composer-send-button {
         display: inline-grid;
         width: 2.35rem;

web/workspace/tests/composer-paste.test.ts

@@ -0,0 +1,121 @@
+import fixtureJson from "../../../tests/fixtures/composer-paste-policy.json" with {
+  type: "json",
+};
+
+import {
+  type ComposerPasteMeasurement,
+  handleComposerPaste,
+  MAX_PLAIN_TEXT_PASTE_CHARS,
+  MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES,
+  measureComposerPaste,
+} from "../src/lib/workspace/console/composer-paste.ts";
+
+declare const Deno: {
+  test(name: string, fn: () => void): void;
+};
+
+function assertEquals(
+  actual: unknown,
+  expected: unknown,
+  message?: string,
+): void {
+  const actualJson = JSON.stringify(actual);
+  const expectedJson = JSON.stringify(expected);
+  if (actualJson !== expectedJson) {
+    throw new Error(
+      `${
+        message ? `${message}: ` : ""
+      }expected ${expectedJson}, got ${actualJson}`,
+    );
+  }
+}
+
+interface FixturePart {
+  value: string;
+  repeat: number;
+}
+
+interface FixtureCase {
+  name: string;
+  parts: FixturePart[];
+  char_count: number;
+  logical_line_count: number;
+  presentation: "text" | "chip";
+}
+
+interface PastePolicyFixture {
+  max_plain_text_chars: number;
+  max_plain_text_logical_lines: number;
+  cases: FixtureCase[];
+}
+
+const fixture = fixtureJson as PastePolicyFixture;
+
+function fixtureContent(testCase: FixtureCase): string {
+  return testCase.parts.map(({ value, repeat }) => value.repeat(repeat)).join(
+    "",
+  );
+}
+
+Deno.test("Browser composer follows the shared paste presentation contract", () => {
+  assertEquals(MAX_PLAIN_TEXT_PASTE_CHARS, fixture.max_plain_text_chars);
+  assertEquals(
+    MAX_PLAIN_TEXT_PASTE_LOGICAL_LINES,
+    fixture.max_plain_text_logical_lines,
+  );
+
+  for (const testCase of fixture.cases) {
+    assertEquals(
+      measureComposerPaste(fixtureContent(testCase)),
+      {
+        charCount: testCase.char_count,
+        logicalLineCount: testCase.logical_line_count,
+        presentation: testCase.presentation,
+      },
+      testCase.name,
+    );
+  }
+});
+
+Deno.test("short paste remains a native Browser edit", () => {
+  let prevented = false;
+  let inserted = 0;
+  const handled = handleComposerPaste(
+    {
+      clipboardData: { getData: () => "replace the selection" },
+      preventDefault: () => {
+        prevented = true;
+      },
+    },
+    () => {
+      inserted += 1;
+    },
+  );
+
+  assertEquals(handled, false);
+  assertEquals(prevented, false);
+  assertEquals(inserted, 0);
+});
+
+Deno.test("chip paste is prevented and routed exactly once", () => {
+  const content = "🦀".repeat(51);
+  let prevented = 0;
+  const inserted: Array<[string, ComposerPasteMeasurement]> = [];
+  const handled = handleComposerPaste(
+    {
+      clipboardData: { getData: () => content },
+      preventDefault: () => {
+        prevented += 1;
+      },
+    },
+    (paste, measurement) => inserted.push([paste, measurement]),
+  );
+
+  assertEquals(handled, true);
+  assertEquals(prevented, 1);
+  assertEquals(inserted, [[content, {
+    charCount: 51,
+    logicalLineCount: 1,
+    presentation: "chip",
+  }]]);
+});