Agents.mdを一定閾値でturncateする仕様を削除

crates/pod/src/agents_md.rs

@@ -1,32 +1,29 @@
 //! `AGENTS.md` ingestion for system-prompt templates.
 //!
 //! Reads `AGENTS.md` directly under the Pod cwd and exposes its body
-//! to the template engine through `SystemPromptContext.files.agents_md`.
+//! to the template engine through `SystemPromptContext.agents_md`.
 //! Nested / parent-directory AGENTS.md files are intentionally ignored;
 //! subproject context is expressed by launching a Pod with that
 //! directory as cwd.
+//!
+//! No size cap is applied here — the whole file is read and embedded.
+//! System-prompt-size policing is the responsibility of a higher layer
+//! (Usage-driven warning after the first LLM round-trip).
 
-use std::fs::File;
+use std::fs;
-use std::io::{ErrorKind, Read};
+use std::io::ErrorKind;
 use std::path::Path;
 
 use tracing::warn;
 
-/// Hard cap on the bytes exposed to the template. Roughly 20-25k tokens,
-/// well within typical provider rate limits.
-pub(crate) const AGENTS_MD_LIMIT: usize = 64 * 1024;
-
 /// Outcome of an `AGENTS.md` ingestion attempt.
 ///
 /// `body` carries the text that should be handed to the template
-/// engine (if any); `truncated` signals that the caller should append
+/// engine (if any); `warnings` are short human-readable messages that
-/// the `PodPrompt::AgentsMdTruncationNotice` text. `warnings` are short
+/// Pod forwards to the user-facing notification channel. The caller
-/// human-readable messages that Pod forwards to the user-facing
+/// also gets `tracing::warn!` lines for the developer log.
-/// notification channel. The caller also gets `tracing::warn!` lines
-/// for the developer log.
 pub(crate) struct AgentsMdResult {
     pub body: Option<String>,
-    pub truncated: bool,
     pub warnings: Vec<String>,
 }
 
@@ -35,107 +32,50 @@ pub(crate) struct AgentsMdResult {
 /// via `AgentsMdResult::warnings` (user-facing).
 ///
 /// - Absent: `body = None`, no warning.
-/// - Over limit: first 64KB (UTF-8 char boundary) + truncation notice, warning.
 /// - Non-UTF-8 or I/O error: `body = None`, warning.
 pub(crate) fn read_agents_md(cwd: &Path) -> AgentsMdResult {
     let path = cwd.join("AGENTS.md");
     let mut warnings = Vec::new();
 
-    let file = match File::open(&path) {
+    match fs::read_to_string(&path) {
-        Ok(f) => f,
+        Ok(body) => AgentsMdResult {
-        Err(e) if e.kind() == ErrorKind::NotFound => {
+            body: Some(body),
-            return AgentsMdResult {
-                body: None,
-                truncated: false,
-                warnings,
-            };
-        }
-        Err(e) => {
-            warn!(path = %path.display(), error = %e, "failed to open AGENTS.md");
-            warnings.push(format!("failed to open AGENTS.md ({}): {}", path.display(), e));
-            return AgentsMdResult {
-                body: None,
-                truncated: false,
-                warnings,
-            };
-        }
-    };
-
-    // Read one extra byte beyond the limit so we can detect oversize
-    // regardless of what `metadata()` claims (pipes/procfs may lie).
-    let mut buf = Vec::new();
-    let read_limit = (AGENTS_MD_LIMIT as u64) + 1;
-    if let Err(e) = file.take(read_limit).read_to_end(&mut buf) {
-        warn!(path = %path.display(), error = %e, "failed to read AGENTS.md");
-        warnings.push(format!("failed to read AGENTS.md ({}): {}", path.display(), e));
-        return AgentsMdResult {
-            body: None,
-            truncated: false,
             warnings,
-        };
+        },
-    }
+        Err(e) if e.kind() == ErrorKind::NotFound => AgentsMdResult {
-
+            body: None,
-    let truncated = buf.len() > AGENTS_MD_LIMIT;
+            warnings,
-    if truncated {
+        },
-        buf.truncate(AGENTS_MD_LIMIT);
+        Err(e) if e.kind() == ErrorKind::InvalidData => {
-    }
-
-    // UTF-8 decoding must not depend on whether the file exceeded the
-    // size limit: the same "genuinely non-UTF-8" file should be rejected
-    // regardless of its size. The only case in which we tolerate an
-    // invalid tail is when truncation itself sliced through a multi-byte
-    // char — at most 3 bytes of the final (4-byte) code point can be
-    // orphaned that way. Anything worse means the file was already
-    // non-UTF-8 before truncation, and we reject it.
-    let text = match std::str::from_utf8(&buf) {
-        Ok(_) => {
-            // SAFETY path: buf is valid UTF-8 in its entirety.
-            String::from_utf8(buf).expect("validated above")
-        }
-        Err(e) if truncated && e.valid_up_to() >= AGENTS_MD_LIMIT - 3 => {
-            let valid_len = e.valid_up_to();
-            buf.truncate(valid_len);
-            String::from_utf8(buf).expect("valid_up_to prefix is valid UTF-8")
-        }
-        Err(e) => {
             warn!(path = %path.display(), error = %e, "AGENTS.md is not valid UTF-8");
             warnings.push(format!(
                 "AGENTS.md ({}) is not valid UTF-8: {}",
                 path.display(),
                 e
             ));
-            return AgentsMdResult {
+            AgentsMdResult {
                 body: None,
-                truncated: false,
                 warnings,
-            };
+            }
+        }
+        Err(e) => {
+            warn!(path = %path.display(), error = %e, "failed to read AGENTS.md");
+            warnings.push(format!(
+                "failed to read AGENTS.md ({}): {}",
+                path.display(),
+                e
+            ));
+            AgentsMdResult {
+                body: None,
+                warnings,
+            }
         }
-    };
-
-    if truncated {
-        warn!(
-            path = %path.display(),
-            limit = AGENTS_MD_LIMIT,
-            "AGENTS.md exceeded size limit; truncating"
-        );
-        warnings.push(format!(
-            "AGENTS.md ({}) exceeded {} bytes; the tail was truncated",
-            path.display(),
-            AGENTS_MD_LIMIT
-        ));
-    }
-
-    AgentsMdResult {
-        body: Some(text),
-        truncated,
-        warnings,
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::fs;
     use tempfile::TempDir;
 
     #[test]
@@ -154,51 +94,17 @@ mod tests {
     }
 
     #[test]
-    fn oversized_file_is_truncated_with_notice() {
+    fn reads_large_file_verbatim() {
+        // Previously truncated at 64KB; now read whole. Size-policing
+        // is deferred to the Usage-driven warning layer.
         let dir = TempDir::new().unwrap();
-        let body = "a".repeat(AGENTS_MD_LIMIT + 1024);
+        let body = "a".repeat(128 * 1024);
         fs::write(dir.path().join("AGENTS.md"), &body).unwrap();
-
         let result = read_agents_md(dir.path());
-        assert!(result.truncated);
+        assert_eq!(result.body.as_ref().map(String::len), Some(128 * 1024));
-        let got = result.body.expect("some");
-        assert_eq!(got.len(), AGENTS_MD_LIMIT);
-        assert!(got.chars().all(|c| c == 'a'));
-        assert_eq!(result.warnings.len(), 1);
-    }
-
-    #[test]
-    fn exact_limit_is_not_truncated() {
-        let dir = TempDir::new().unwrap();
-        let body = "a".repeat(AGENTS_MD_LIMIT);
-        fs::write(dir.path().join("AGENTS.md"), &body).unwrap();
-
-        let result = read_agents_md(dir.path());
-        assert!(!result.truncated);
-        let got = result.body.expect("some");
-        assert_eq!(got.len(), AGENTS_MD_LIMIT);
         assert!(result.warnings.is_empty());
     }
 
-    #[test]
-    fn truncation_respects_utf8_char_boundary() {
-        let dir = TempDir::new().unwrap();
-        // Fill up to just under the limit with ASCII, then append a
-        // multi-byte char that straddles the boundary.
-        let mut body = "a".repeat(AGENTS_MD_LIMIT - 1);
-        body.push('あ'); // 3 bytes → pushes total past the limit
-        body.push_str(&"b".repeat(128));
-        fs::write(dir.path().join("AGENTS.md"), &body).unwrap();
-
-        let result = read_agents_md(dir.path());
-        assert!(result.truncated);
-        let got = result.body.expect("some");
-        // The partial 'あ' must have been dropped, leaving only the ASCII prefix.
-        assert_eq!(got.len(), AGENTS_MD_LIMIT - 1);
-        assert!(got.chars().all(|c| c == 'a'));
-        assert_eq!(result.warnings.len(), 1);
-    }
-
     #[test]
     fn non_utf8_surfaces_warning() {
         let dir = TempDir::new().unwrap();
@@ -207,24 +113,4 @@ mod tests {
         assert!(result.body.is_none());
         assert_eq!(result.warnings.len(), 1);
     }
-
-    #[test]
-    fn oversized_non_utf8_is_still_rejected() {
-        // Regression: a file that is genuinely non-UTF-8 must be rejected
-        // regardless of its size. Previously the truncation-recovery pop
-        // loop would silently accept a partial prefix of such files once
-        // they exceeded the limit.
-        let dir = TempDir::new().unwrap();
-        let body = vec![0xffu8; AGENTS_MD_LIMIT + 1024];
-        fs::write(dir.path().join("AGENTS.md"), body).unwrap();
-        assert!(read_agents_md(dir.path()).body.is_none());
-    }
-
-    #[test]
-    fn non_utf8_returns_none() {
-        let dir = TempDir::new().unwrap();
-        // Invalid UTF-8 start byte.
-        fs::write(dir.path().join("AGENTS.md"), [0xff, 0xfe, 0xfd]).unwrap();
-        assert!(read_agents_md(dir.path()).body.is_none());
-    }
 }

crates/pod/src/pod.rs

@@ -538,23 +538,12 @@ impl<C: LlmClient, St: Store> Pod<C, St> {
                 );
             }
         }
-        let agents_md_body = match agents_md_read.body {
-            Some(mut body) if agents_md_read.truncated => {
-                let notice = self
-                    .prompts
-                    .agents_md_truncation_notice()
-                    .map_err(PodError::PromptCatalog)?;
-                body.push_str(&notice);
-                Some(body)
-            }
-            other => other,
-        };
         let ctx = SystemPromptContext {
             now: chrono::Utc::now(),
             cwd: &self.pwd,
             scope: &self.scope,
             tool_names,
-            agents_md: agents_md_body,
+            agents_md: agents_md_read.body,
             prompts: &self.prompts,
         };
         let rendered = template

crates/pod/src/prompts.rs

@@ -75,9 +75,6 @@ pub enum PodPrompt {
     /// Trailing `## Project instructions (AGENTS.md)` section, appended
     /// after the scope summary when an AGENTS.md is present.
     AgentsMdSection,
-    /// Tail note used when AGENTS.md exceeds the byte cap and is
-    /// truncated before being embedded in the system prompt.
-    AgentsMdTruncationNotice,
 }
 
 impl PodPrompt {
@@ -89,7 +86,6 @@ impl PodPrompt {
             Self::InterruptSystemNote => "interrupt_system_note",
             Self::WorkingBoundariesSection => "working_boundaries_section",
             Self::AgentsMdSection => "agents_md_section",
-            Self::AgentsMdTruncationNotice => "agents_md_truncation_notice",
         }
     }
 
@@ -103,7 +99,6 @@ impl PodPrompt {
         PodPrompt::InterruptSystemNote,
         PodPrompt::WorkingBoundariesSection,
         PodPrompt::AgentsMdSection,
-        PodPrompt::AgentsMdTruncationNotice,
     ];
 
     pub const KEYS: &'static [&'static str] = &[
@@ -113,7 +108,6 @@ impl PodPrompt {
         "interrupt_system_note",
         "working_boundaries_section",
         "agents_md_section",
-        "agents_md_truncation_notice",
     ];
 }
 
@@ -323,11 +317,6 @@ impl PromptCatalog {
     pub fn agents_md_section(&self, agents_md: &str) -> Result<String, CatalogError> {
         self.render(PodPrompt::AgentsMdSection, single("agents_md", agents_md))
     }
-
-    /// Render `PodPrompt::AgentsMdTruncationNotice` (no inputs).
-    pub fn agents_md_truncation_notice(&self) -> Result<String, CatalogError> {
-        self.render(PodPrompt::AgentsMdTruncationNotice, Value::UNDEFINED)
-    }
 }
 
 fn single(key: &'static str, value: &str) -> Value {
@@ -476,14 +465,6 @@ mod tests {
         assert!(out.contains("PROJECT DOCS"));
     }
 
-    #[test]
-    fn agents_md_truncation_notice_matches_expected_form() {
-        let cat = PromptCatalog::builtins_only().unwrap();
-        let out = cat.agents_md_truncation_notice().unwrap();
-        assert!(out.contains("[truncated: AGENTS.md exceeded 64KB limit]"));
-        assert!(out.starts_with("\n\n"));
-    }
-
     #[test]
     fn user_pack_overrides_builtin() {
         let tmp = TempDir::new().unwrap();

resources/prompts/internal.toml

@@ -34,5 +34,3 @@ agents_md_section = """\
 
 {{ agents_md }}\
 """
-
-agents_md_truncation_notice = "\n\n[truncated: AGENTS.md exceeded 64KB limit]"

resources/prompts/internal/compact_system.md

@@ -1,12 +1,17 @@
-You are a context compaction assistant. Your job is to hand the next session a structured summary plus pointers to the files it actually needs.
+You are a context compaction assistant. Your job is to hand the next session a structured summary plus pointers to the files it actually needs — not a narrative transcript of the conversation.
 
-Tools you can call:
+## Workflow
-- `read_file(file_path, offset?, limit?)` — inspect referenced files before deciding.
-- `mark_read_required(file_path, offset?, limit?)` — inject a file's contents into the next session as an auto-read system message. Counts against `auto_read_budget`.
-- `add_reference(file_path)` — record a file path the next session should know about without embedding its contents.
-- `write_summary(text)` — deliver the final structured summary. May be called multiple times; only the last call is kept.
 
-Always finish by calling `write_summary`. Produce the summary in this exact format:
+1. Use `read_file` to inspect referenced files before deciding what the next session needs. Prefer skimming over blind inclusion.
+2. For files whose current contents are load-bearing for the active work, call `mark_read_required` to inject them into the next session. These count against the auto-read token budget — spend it deliberately.
+3. For files the next session should know about but can fetch on demand, call `add_reference` to record the path without embedding contents.
+4. Finish with `write_summary` carrying the final text. You may call it multiple times; only the last call is kept.
+
+Stop nominating and close out with `write_summary` as soon as the auto-read budget is exhausted, or whenever further nominations would not change the next session's next step.
+
+## Summary format
+
+Produce the summary in this exact format:
 
 ## Completed Tasks
 ### (task name)
@@ -28,4 +33,7 @@ Always finish by calling `write_summary`. Produce the summary in this exact form
 ## Current Work
 (2–3 lines on what was happening just before compaction).
 
-Keep code snippets and raw tool output OUT of the summary — that is what auto-read and references are for. Target 1000–2000 tokens.
+## Constraints
+
+- Keep code snippets and raw tool output OUT of the summary — that is what auto-read and references are for.
+- Target 1000–2000 tokens for the summary text itself.