use std::collections::VecDeque;
use std::time::Instant;

use protocol::{
    AlertLevel, AlertSource, CompletionEntry, CompletionKind, Event, Method, PodStatus, RunResult,
    Segment,
};

use crate::block::{
    Block, CompactEvent, ThinkingBlock, ThinkingState, ToolCallBlock, ToolCallState,
};
use crate::cache::FileCache;
use crate::command::{CommandEnvironment, CommandExecution, CommandInputMode, CommandRegistry};
use crate::input::InputBuffer;
use crate::scroll::Scroll;
use crate::task::TaskStore;
use crate::ui::Mode;

/// In-flight completion popup state. Lives on `App` while the user is
/// typing inside a `@` / `#` / `/` token. Cleared whenever the trigger
/// is invalidated (cursor moved out, whitespace landed inside the
/// token, the sigil was deleted, or the candidate was confirmed).
pub struct CompletionState {
    pub kind: CompletionKind,
    /// Atom index of the leading sigil (`@` / `#` / `/`).
    pub prefix_start: usize,
    /// Text typed after the sigil (sigil itself excluded).
    pub prefix: String,
    /// Latest candidate set returned by the Pod for `(kind, prefix)`.
    /// Initially empty until `Event::Completions` lands.
    pub entries: Vec<CompletionEntry>,
    pub selected: usize,
}

impl CompletionState {
    pub fn is_active(&self) -> bool {
        !self.entries.is_empty()
    }

    /// Maximum rows the popup ever renders. Caller can clip to fewer
    /// rows if vertical space is tight.
    pub const MAX_VISIBLE: usize = 6;
}

struct RollbackSubmitState {
    text: String,
    segments: Vec<Segment>,
    block_start: usize,
    turn_before: usize,
}

#[derive(Clone)]
pub struct QueuedInput {
    segments: Vec<Segment>,
    preview: String,
}

impl QueuedInput {
    fn new(segments: Vec<Segment>) -> Self {
        let preview = Segment::flatten_to_text(&segments);
        Self { segments, preview }
    }

    pub fn preview(&self) -> &str {
        &self.preview
    }
}

pub struct App {
    pub pod_name: String,
    pub connected: bool,
    /// Last controller status reported by the Pod. Drives the status line
    /// and Ctrl-key routing; do not infer this solely from replayed history.
    pub pod_status: PodStatus,
    /// True while the Pod is in `PodStatus::Running`.
    pub running: bool,
    /// True while the Pod is in `PodStatus::Paused`.
    pub paused: bool,
    pub run_requests: usize,
    /// Sum of `input_tokens - cache_read_input_tokens` across the
    /// current turn's LLM requests — i.e. the net tokens this turn
    /// actually had to upload at full price (cache writes included,
    /// cache reads excluded). Reset on `RunEnd`.
    pub run_upload_tokens: u64,
    pub run_output_tokens: u64,
    /// Latest session context tokens reported by the Pod. This is the raw
    /// `input_tokens` value and is independent from per-run upload totals.
    pub session_context_tokens: u64,
    pub context_window: u64,
    pub turn_index: usize,
    pub current_tool: Option<String>,
    /// Normal composer input that is submitted as `Method::Run`.
    pub input: InputBuffer,
    /// Separate command-line input. It is never submitted as a user message.
    pub command_input: InputBuffer,
    pub input_mode: CommandInputMode,
    pub command_registry: CommandRegistry,
    pub quit: bool,
    /// 2-tap guard for `Ctrl-C` when the Pod is not running. First press
    /// records the instant; a second press within the timeout exits the
    /// TUI (the Pod itself stays alive).
    pub quit_confirm: Option<std::time::Instant>,
    /// Full display history in render order.
    pub blocks: Vec<Block>,
    pub scroll: Scroll,
    pub mode: Mode,
    pub cache: FileCache,
    /// True when the latest AssistantText block is still being streamed
    /// and future text deltas should append to it instead of starting a
    /// fresh block.
    assistant_streaming: bool,
    /// Completion popup state, when an `@` / `#` / `/` token is in
    /// flight. `None` whenever the trigger conditions don't hold.
    pub completion: Option<CompletionState>,
    /// In-TUI mirror of the Pod's session task store, reconstructed
    /// directly from observed `TaskCreate` / `TaskUpdate` tool calls and
    /// `[Session TaskStore snapshot]` system messages — no protocol
    /// surface added on the Pod side.
    pub task_store: TaskStore,
    /// Whether the right-side task pane is currently open.
    pub task_pane_open: bool,
    /// Top entry index of the task pane's visible window. Clamped on
    /// render so it never points past the end of the list.
    pub task_pane_scroll: usize,
    /// TUI-local FIFO of user inputs submitted while the Pod is already running.
    /// Entries have not been sent to the Pod yet, so they remain editable/cancellable locally.
    queued_inputs: VecDeque<QueuedInput>,
    /// Local submit state kept until the accepted run either completes
    /// normally or reports that the empty assistant turn was rolled back.
    pending_submit_rollback: Option<RollbackSubmitState>,
    /// Last rolled-back submit that could not be restored because the
    /// composer already contained unsent user input.
    last_rolled_back_input: Option<Vec<Segment>>,
}

impl App {
    pub fn new(pod_name: String) -> Self {
        Self {
            pod_name,
            connected: false,
            pod_status: PodStatus::Idle,
            running: false,
            paused: false,
            run_requests: 0,
            run_upload_tokens: 0,
            run_output_tokens: 0,
            session_context_tokens: 0,
            context_window: 0,
            turn_index: 0,
            current_tool: None,
            input: InputBuffer::new(),
            command_input: InputBuffer::new(),
            input_mode: CommandInputMode::Composer,
            command_registry: CommandRegistry::default(),
            quit: false,
            quit_confirm: None,
            blocks: Vec::new(),
            scroll: Scroll::default(),
            mode: Mode::Normal,
            cache: FileCache::new(),
            assistant_streaming: false,
            completion: None,
            task_store: TaskStore::new(),
            task_pane_open: false,
            task_pane_scroll: 0,
            queued_inputs: VecDeque::new(),
            pending_submit_rollback: None,
            last_rolled_back_input: None,
        }
    }

    pub fn toggle_task_pane(&mut self) {
        self.task_pane_open = !self.task_pane_open;
        if !self.task_pane_open {
            self.task_pane_scroll = 0;
        }
    }

    pub fn scroll_task_pane_up(&mut self, n: usize) {
        self.task_pane_scroll = self.task_pane_scroll.saturating_sub(n);
    }

    pub fn scroll_task_pane_down(&mut self, n: usize) {
        self.task_pane_scroll = self.task_pane_scroll.saturating_add(n);
    }

    pub fn set_pod_status(&mut self, status: PodStatus) {
        self.pod_status = status;
        self.running = status == PodStatus::Running;
        self.paused = status == PodStatus::Paused;
        if self.running {
            self.quit_confirm = None;
        }
    }

    /// Re-evaluate the completion popup against the current input.
    /// Returns a `Method::ListCompletions` to send when the
    /// `(kind, prefix_start, prefix)` triple changed; otherwise `None`.
    /// Callers should invoke this after every input mutation that could
    /// move the cursor or change atoms.
    pub fn refresh_completion(&mut self) -> Option<Method> {
        if self.is_command_mode() {
            self.completion = None;
            return None;
        }
        match self.input.pending_completion_prefix() {
            Some((kind, start, prefix)) => {
                let need_query = match &self.completion {
                    Some(c) => c.kind != kind || c.prefix_start != start || c.prefix != prefix,
                    None => true,
                };
                let entries = match self.completion.take() {
                    Some(c) if c.kind == kind && c.prefix_start == start => c.entries,
                    _ => Vec::new(),
                };
                self.completion = Some(CompletionState {
                    kind,
                    prefix_start: start,
                    prefix: prefix.clone(),
                    entries,
                    selected: 0,
                });
                if need_query {
                    Some(Method::ListCompletions { kind, prefix })
                } else {
                    None
                }
            }
            None => {
                self.completion = None;
                None
            }
        }
    }

    pub fn move_completion_up(&mut self) {
        if let Some(c) = self.completion.as_mut()
            && !c.entries.is_empty()
        {
            c.selected = if c.selected == 0 {
                c.entries.len() - 1
            } else {
                c.selected - 1
            };
        }
    }

    pub fn move_completion_down(&mut self) {
        if let Some(c) = self.completion.as_mut()
            && !c.entries.is_empty()
        {
            c.selected = (c.selected + 1) % c.entries.len();
        }
    }

    pub fn cancel_completion(&mut self) {
        self.completion = None;
    }

    /// Tab path: insert the popup-selected entry's value (with a
    /// trailing `/` when it's a directory) as raw text replacing the
    /// in-flight `@<typed>` portion. The popup state is preserved so
    /// the re-evaluated trigger can fetch fresh candidates for the new
    /// prefix (drill-in for directories, narrow-to-one for files).
    /// Returns the follow-up `Method::ListCompletions` to send when
    /// the new prefix differs from the old one.
    pub fn apply_completion_text(&mut self) -> Option<Method> {
        let state = self.completion.as_ref()?;
        if state.entries.is_empty() {
            return None;
        }
        let entry = &state.entries[state.selected];
        let text = if entry.is_dir {
            format!("{}/", entry.value)
        } else {
            entry.value.clone()
        };
        // `prefix_start` indexes the sigil atom; the text we want to
        // replace lives just after it (sigil itself stays).
        let typed_start = state.prefix_start + 1;
        self.input.replace_with_text_at(typed_start, &text);
        self.refresh_completion()
    }

    /// Space path: replace the `@<typed>` range with a chip atom and
    /// clear the popup if `prefix` (= the text the user has typed
    /// after the sigil) resolves to a confirmable target. Three
    /// matching modes:
    ///
    /// 1. **Direct value match**: some entry's `value` equals `prefix`
    ///    (covers files and slash-less directory form).
    /// 2. **Slashed directory match**: some directory entry's
    ///    `value + "/"` equals `prefix` (the form Tab inserts).
    /// 3. **Drilled-into-directory match**: `prefix` ends with `/`
    ///    and at least one entry lives under it.
    ///
    /// Directory chips always carry a trailing `/` so the rendered
    /// label reads `@crates/`.
    ///
    /// `selected` is intentionally ignored — terminating with a
    /// space is a typed-based "I'm done with this token" signal,
    /// so a race-y top entry shouldn't block confirmation when the
    /// typed text matches another entry.
    pub fn chipify_completion_if_exact_match(&mut self) -> bool {
        let Some(state) = self.completion.as_ref() else {
            return false;
        };
        let direct = state
            .entries
            .iter()
            .find(|e| {
                state.prefix == e.value || (e.is_dir && state.prefix == format!("{}/", e.value))
            })
            .map(|e| {
                if e.is_dir {
                    format!("{}/", e.value)
                } else {
                    e.value.clone()
                }
            });
        let drilled = (direct.is_none() && state.prefix.ends_with('/'))
            .then(|| {
                state
                    .entries
                    .iter()
                    .any(|e| e.value.starts_with(&state.prefix))
                    .then(|| state.prefix.clone())
            })
            .flatten();
        let Some(value) = direct.or(drilled) else {
            return false;
        };
        let kind = state.kind;
        let start = state.prefix_start;
        match kind {
            CompletionKind::File => self.input.replace_with_file_ref(start, value),
            CompletionKind::Knowledge => self.input.replace_with_knowledge_ref(start, value),
            CompletionKind::Workflow => self.input.replace_with_workflow_invoke(start, value),
        }
        self.completion = None;
        true
    }

    /// Enter path: commit the currently *selected* popup entry,
    /// regardless of how much of its value the user has typed. This
    /// is the popup-UI sense of "Enter accepts the highlighted
    /// suggestion" — partial typing like `@README.` followed by
    /// Enter should chip when the popup is on `README.md`.
    ///
    /// Files (and Knowledge / Workflow entries, which have no dir
    /// concept) chipify here. Directory file entries return `false`
    /// so the caller can fall through to `apply_completion_text`
    /// for drill-in — chip-ifying a directory on Enter would strand
    /// the user with no way to inspect children.
    pub fn chipify_selected_completion_if_committable(&mut self) -> bool {
        let Some(state) = self.completion.as_ref() else {
            return false;
        };
        if state.entries.is_empty() {
            return false;
        }
        let entry = &state.entries[state.selected];
        if state.kind == CompletionKind::File && entry.is_dir {
            return false;
        }
        let kind = state.kind;
        let start = state.prefix_start;
        let value = entry.value.clone();
        match kind {
            CompletionKind::File => self.input.replace_with_file_ref(start, value),
            CompletionKind::Knowledge => self.input.replace_with_knowledge_ref(start, value),
            CompletionKind::Workflow => self.input.replace_with_workflow_invoke(start, value),
        }
        self.completion = None;
        true
    }

    pub fn submit_input(&mut self) -> Option<Method> {
        let segments = self.input.submit_segments();
        if segments_are_blank(&segments) {
            // Empty Enter only does something meaningful when the Pod
            // is paused: resume the interrupted turn. Otherwise no-op.
            if self.paused {
                self.input.clear();
                return Some(Method::Resume);
            }
            return None;
        }
        if self.running {
            self.queued_inputs.push_back(QueuedInput::new(segments));
            self.input.clear();
            self.completion = None;
            return None;
        }
        self.input.clear();
        Some(self.method_for_run(segments))
    }

    fn method_for_run(&mut self, segments: Vec<Segment>) -> Method {
        // TurnHeader / UserMessage blocks are pushed in response to
        // `Event::UserMessage` (single source of truth, shared by every
        // client subscribed to the Pod). Locally we only clear the
        // input buffer and forward the method, while remembering enough
        // local state to undo the visible submit if the Pod reports that
        // the accepted run produced no assistant output and was rolled back.
        self.pending_submit_rollback = Some(RollbackSubmitState {
            text: Segment::flatten_to_text(&segments),
            segments: segments.clone(),
            block_start: self.blocks.len(),
            turn_before: self.turn_index,
        });
        Method::Run { input: segments }
    }

    pub fn queued_input_count(&self) -> usize {
        self.queued_inputs.len()
    }

    pub fn next_queued_input_preview(&self) -> Option<&str> {
        self.queued_inputs.front().map(QueuedInput::preview)
    }

    pub fn clear_queued_inputs(&mut self) -> usize {
        let cleared = self.queued_inputs.len();
        self.queued_inputs.clear();
        cleared
    }

    pub fn restore_next_queued_input_to_composer(&mut self) -> bool {
        if self.queued_inputs.is_empty() {
            return false;
        }
        if !self.input.is_empty() {
            self.push_error("Composer is not empty; clear it before editing queued input.");
            return false;
        }
        let Some(queued) = self.queued_inputs.pop_front() else {
            return false;
        };
        self.input.replace_with_segments(&queued.segments);
        self.completion = None;
        true
    }

    fn pop_next_queued_run(&mut self) -> Option<Method> {
        let queued = self.queued_inputs.pop_front()?;
        Some(self.method_for_run(queued.segments))
    }

    pub fn push_error(&mut self, message: impl Into<String>) {
        self.blocks.push(Block::Alert {
            level: AlertLevel::Error,
            source: AlertSource::Pod,
            message: message.into(),
        });
    }

    fn push_history_item(&mut self, item: &serde_json::Value) {
        let item_type = item["type"].as_str().unwrap_or("");
        match item_type {
            "message" => {
                let role = item["role"].as_str().unwrap_or("");
                let text = message_text(item);
                match role {
                    "user" => {
                        self.turn_index += 1;
                        self.blocks.push(Block::TurnHeader {
                            turn: self.turn_index,
                        });
                        // Pod attaches the original `Vec<Segment>` to user
                        // messages from live submissions, so we can rebuild
                        // typed atoms (paste chips, refs) here. Seed history
                        // loaded post-compaction has no `segments` field —
                        // fall back to a single text segment.
                        let segments = item
                            .get("segments")
                            .and_then(|v| serde_json::from_value::<Vec<Segment>>(v.clone()).ok())
                            .unwrap_or_else(|| {
                                if text.is_empty() {
                                    Vec::new()
                                } else {
                                    vec![Segment::text(text.clone())]
                                }
                            });
                        if !segments.is_empty() {
                            self.blocks.push(Block::UserMessage { segments });
                        }
                    }
                    "assistant" if !text.is_empty() => {
                        self.blocks.push(Block::AssistantText { text });
                    }
                    "system" if !text.is_empty() => {
                        self.task_store.apply_system_message_text(&text);
                        self.blocks.push(Block::SystemMessage { text });
                    }
                    _ => {}
                }
            }
            "tool_call" => {
                // `Item::ToolCall` serializes the linking key as
                // `call_id`; `id` is a separate optional item-level
                // identifier. Use `call_id` so this matches how
                // Event::ToolCallStart populates the block.
                let id = item["call_id"].as_str().unwrap_or("").to_owned();
                let name = item["name"].as_str().unwrap_or("?").to_owned();
                let arguments = item["arguments"].as_str().map(|s| s.to_owned());
                if let Some(args) = arguments.as_deref() {
                    self.task_store.apply_tool_call(&name, args);
                }
                self.blocks.push(Block::ToolCall(ToolCallBlock {
                    id,
                    name,
                    args_stream: arguments.clone().unwrap_or_default(),
                    arguments,
                    state: ToolCallState::Executing,
                    edit_snapshot: None,
                }));
            }
            "reasoning" => {
                let text = item["text"].as_str().unwrap_or("").to_owned();
                let body = if text.is_empty() {
                    item["summary"]
                        .as_array()
                        .map(|arr| {
                            arr.iter()
                                .filter_map(|v| v.as_str())
                                .collect::<Vec<_>>()
                                .join("\n")
                        })
                        .unwrap_or_default()
                } else {
                    text
                };
                self.blocks.push(Block::Thinking(ThinkingBlock {
                    text: body,
                    state: ThinkingState::Finished { elapsed_secs: None },
                }));
            }
            "tool_result" => {
                let id = item["call_id"].as_str().unwrap_or("").to_owned();
                let summary = item["summary"].as_str().unwrap_or("").to_owned();
                let output = item["content"].as_str().map(|s| s.to_owned());
                let is_error = item["is_error"].as_bool().unwrap_or(false);
                let (name, args) = self
                    .find_tool_call_mut(&id)
                    .map(|b| (b.name.clone(), b.arguments.clone()))
                    .unwrap_or_default();
                let edit_snapshot = if !is_error && name == "Edit" {
                    args.as_deref()
                        .and_then(|s| serde_json::from_str::<serde_json::Value>(s).ok())
                        .and_then(|v| v["file_path"].as_str().map(|s| s.to_owned()))
                        .and_then(|path| self.cache.get(&path).map(|s| s.to_owned()))
                } else {
                    None
                };
                if let Some(tc) = self.find_tool_call_mut(&id) {
                    if edit_snapshot.is_some() {
                        tc.edit_snapshot = edit_snapshot;
                    }
                    tc.state = if is_error {
                        ToolCallState::Error {
                            summary,
                            output: output.clone(),
                        }
                    } else {
                        ToolCallState::Done {
                            summary,
                            output: output.clone(),
                        }
                    };
                    if !is_error {
                        apply_cache_update(
                            &mut self.cache,
                            &name,
                            args.as_deref(),
                            output.as_deref(),
                        );
                    }
                }
            }
            _ => {}
        }
    }

    pub fn handle_pod_event(&mut self, event: Event) -> Option<Method> {
        match event {
            Event::UserMessage { segments } => {
                self.turn_index += 1;
                self.blocks.push(Block::TurnHeader {
                    turn: self.turn_index,
                });
                self.blocks.push(Block::UserMessage { segments });
                self.assistant_streaming = false;
            }
            Event::SegmentRotated { entry } => {
                self.reset_for_rotation();
                self.apply_log_entry_raw(&entry);
                self.assistant_streaming = false;
            }
            Event::SystemItem { item } => {
                self.apply_system_item(&item);
                self.assistant_streaming = false;
            }
            Event::TurnStart { .. } => {
                self.set_pod_status(PodStatus::Running);
                self.run_requests += 1;
                self.current_tool = None;
                self.assistant_streaming = false;
            }
            // UI consumers of Invoke / LlmCall semantics are out of scope
            // for `tickets/invoke-turn-llmcall-semantics.md`; events flow
            // through to subscribers but the TUI currently derives its
            // turn header from `UserMessage` / `SystemItem` arrivals.
            Event::InvokeStart { .. } | Event::LlmCallStart { .. } | Event::LlmCallEnd { .. } => {}
            Event::TextDelta { text } => {
                self.append_assistant_text(&text);
            }
            Event::TextDone { .. } => {
                self.assistant_streaming = false;
            }
            Event::ThinkingStart => {
                self.assistant_streaming = false;
                self.blocks.push(Block::Thinking(ThinkingBlock {
                    text: String::new(),
                    state: ThinkingState::Streaming {
                        started_at: Instant::now(),
                    },
                }));
            }
            Event::ThinkingDelta { text } => {
                if let Some(b) = self.last_streaming_thinking_mut() {
                    b.text.push_str(&text);
                }
            }
            Event::ThinkingDone { text } => {
                if let Some(b) = self.last_streaming_thinking_mut() {
                    // Delta-accumulated text wins. `text` here is the
                    // Done payload (full body), used only as a fallback
                    // for providers that don't stream deltas.
                    if b.text.is_empty() {
                        b.text = text;
                    }
                    let elapsed = match &b.state {
                        ThinkingState::Streaming { started_at } => {
                            Some(started_at.elapsed().as_secs())
                        }
                        _ => None,
                    };
                    b.state = ThinkingState::Finished {
                        elapsed_secs: elapsed,
                    };
                }
            }
            Event::TurnEnd { .. } => {
                self.assistant_streaming = false;
                self.mark_orphan_tool_calls_incomplete();
                self.mark_orphan_thinking_incomplete();
                self.current_tool = None;
            }
            Event::ToolCallStart { id, name } => {
                self.current_tool = Some(name.clone());
                self.assistant_streaming = false;
                self.blocks.push(Block::ToolCall(ToolCallBlock {
                    id,
                    name,
                    args_stream: String::new(),
                    arguments: None,
                    state: ToolCallState::Pending,
                    edit_snapshot: None,
                }));
            }
            Event::ToolCallArgsDelta { id, json } => {
                if let Some(b) = self.find_tool_call_mut(&id) {
                    b.args_stream.push_str(&json);
                    if matches!(b.state, ToolCallState::Pending) {
                        b.state = ToolCallState::Streaming;
                    }
                }
            }
            Event::ToolCallDone { id, arguments, .. } => {
                self.current_tool = None;
                let name = self.find_tool_call_mut(&id).map(|b| b.name.clone());
                if let Some(name) = name.as_deref() {
                    self.task_store.apply_tool_call(name, &arguments);
                }
                if let Some(b) = self.find_tool_call_mut(&id) {
                    b.arguments = Some(arguments);
                    // Only advance the state when it's still in-flight.
                    // If a ToolResult arrived out of order and already
                    // transitioned us to Done/Error, keep that.
                    if matches!(b.state, ToolCallState::Pending | ToolCallState::Streaming) {
                        b.state = ToolCallState::Executing;
                    }
                }
            }
            Event::ToolResult {
                id,
                summary,
                output,
                is_error,
            } => {
                // Pull the name / args out first so we can look at the
                // (immutable) cache before taking the mutable block
                // borrow below.
                let (name, args) = self
                    .find_tool_call_mut(&id)
                    .map(|b| (b.name.clone(), b.arguments.clone()))
                    .unwrap_or_default();
                let edit_snapshot = if !is_error && name == "Edit" {
                    args.as_deref()
                        .and_then(|s| serde_json::from_str::<serde_json::Value>(s).ok())
                        .and_then(|v| v["file_path"].as_str().map(|s| s.to_owned()))
                        .and_then(|path| self.cache.get(&path).map(|s| s.to_owned()))
                } else {
                    None
                };

                if let Some(b) = self.find_tool_call_mut(&id) {
                    if edit_snapshot.is_some() {
                        b.edit_snapshot = edit_snapshot;
                    }
                    b.state = if is_error {
                        ToolCallState::Error {
                            summary,
                            output: output.clone(),
                        }
                    } else {
                        ToolCallState::Done {
                            summary,
                            output: output.clone(),
                        }
                    };
                    if !is_error {
                        apply_cache_update(
                            &mut self.cache,
                            &name,
                            args.as_deref(),
                            output.as_deref(),
                        );
                    }
                } else {
                    // Result for an unknown tool call. Surface it as an
                    // alert so it isn't silently dropped.
                    let level = if is_error {
                        AlertLevel::Error
                    } else {
                        AlertLevel::Warn
                    };
                    self.blocks.push(Block::Alert {
                        level,
                        source: AlertSource::Pod,
                        message: format!("orphan tool result ({id}): {summary}"),
                    });
                }
            }
            Event::Usage {
                input_tokens,
                output_tokens,
                cache_read_input_tokens,
            } => {
                self.session_context_tokens = input_tokens.unwrap_or(0);
                // Subtract the cache-hit portion so a tool loop that
                // re-sends the same prefix on every request doesn't
                // re-count it. cache_creation stays in (it is full
                // price on this request).
                let net_input = input_tokens
                    .unwrap_or(0)
                    .saturating_sub(cache_read_input_tokens.unwrap_or(0));
                self.run_upload_tokens += net_input;
                self.run_output_tokens += output_tokens.unwrap_or(0);
            }
            Event::Error { code, message } => {
                self.push_error(format!("[{code:?}] {message}"));
            }
            Event::RunEnd { result } => {
                if matches!(result, RunResult::RolledBack) {
                    self.handle_rolled_back_run();
                } else {
                    self.blocks.push(Block::TurnStats {
                        requests: self.run_requests,
                        upload_tokens: self.run_upload_tokens,
                        output_tokens: self.run_output_tokens,
                    });
                    self.pending_submit_rollback = None;
                    self.reset_run_state(match result {
                        RunResult::Paused => PodStatus::Paused,
                        RunResult::Finished | RunResult::LimitReached | RunResult::RolledBack => {
                            PodStatus::Idle
                        }
                    });
                    if matches!(result, RunResult::Finished | RunResult::LimitReached) {
                        return self.pop_next_queued_run();
                    }
                }
            }
            Event::CompactStart => {
                self.blocks.push(Block::Compact(CompactEvent::Streaming {
                    started_at: Instant::now(),
                }));
            }
            Event::CompactDone { new_segment_id } => {
                self.session_context_tokens = 0;
                if let Some(evt) = self.last_streaming_compact_mut() {
                    let elapsed_secs = match evt {
                        CompactEvent::Streaming { started_at } => {
                            Some(started_at.elapsed().as_secs())
                        }
                        _ => None,
                    };
                    *evt = CompactEvent::Done {
                        new_segment_id,
                        elapsed_secs,
                    };
                } else {
                    self.blocks.push(Block::Compact(CompactEvent::Done {
                        new_segment_id,
                        elapsed_secs: None,
                    }));
                }
            }
            Event::CompactFailed { error } => {
                if let Some(evt) = self.last_streaming_compact_mut() {
                    let elapsed_secs = match evt {
                        CompactEvent::Streaming { started_at } => {
                            Some(started_at.elapsed().as_secs())
                        }
                        _ => None,
                    };
                    *evt = CompactEvent::Failed {
                        error,
                        elapsed_secs,
                    };
                } else {
                    self.blocks.push(Block::Compact(CompactEvent::Failed {
                        error,
                        elapsed_secs: None,
                    }));
                }
            }
            Event::Alert(alert) => {
                self.blocks.push(Block::Alert {
                    level: alert.level,
                    source: alert.source,
                    message: alert.message,
                });
            }
            Event::Snapshot {
                entries,
                greeting,
                status,
            } => {
                self.restore_snapshot(&entries, greeting);
                self.set_pod_status(status);
            }
            Event::Status { status } => {
                self.set_pod_status(status);
            }
            Event::Completions { kind, entries } => {
                // Apply only if the popup is still on the same
                // (kind, prefix) the request was issued for; an
                // out-of-date reply (the user typed past it) is dropped.
                if let Some(state) = self.completion.as_mut()
                    && state.kind == kind
                {
                    state.entries = entries;
                    state.selected = 0;
                }
            }
            Event::VisiblePods { .. }
            | Event::PodInspection { .. }
            | Event::PodAttachRestore { .. } => {}
            Event::Shutdown => {
                self.mark_orphan_compacts_incomplete();
                self.quit = true;
            }
        }
        None
    }

    fn reset_run_state(&mut self, status: PodStatus) {
        self.set_pod_status(status);
        self.run_requests = 0;
        self.run_upload_tokens = 0;
        self.run_output_tokens = 0;
        self.current_tool = None;
        self.assistant_streaming = false;
    }

    fn handle_rolled_back_run(&mut self) {
        let hint = if let Some(state) = self.pending_submit_rollback.take() {
            self.blocks
                .truncate(state.block_start.min(self.blocks.len()));
            self.turn_index = state.turn_before;
            if self.input.is_empty() {
                self.input.replace_with_segments(&state.segments);
                self.completion = None;
                self.last_rolled_back_input = None;
                "Rolled back empty assistant turn; restored your input.".to_owned()
            } else {
                let preview = rollback_input_preview(&state.text);
                self.last_rolled_back_input = Some(state.segments);
                format!(
                    "Rolled back empty assistant turn; composer was not empty, kept submitted input in backup: {preview}"
                )
            }
        } else {
            "Rolled back empty assistant turn; no local submitted input was available to restore."
                .to_owned()
        };
        self.reset_run_state(PodStatus::Idle);
        self.blocks.push(Block::Alert {
            level: AlertLevel::Warn,
            source: AlertSource::Pod,
            message: hint,
        });
    }

    fn append_assistant_text(&mut self, text: &str) {
        if self.assistant_streaming {
            if let Some(Block::AssistantText { text: existing }) = self.blocks.last_mut() {
                existing.push_str(text);
                return;
            }
        }
        self.blocks.push(Block::AssistantText {
            text: text.to_owned(),
        });
        self.assistant_streaming = true;
    }

    /// Walk the most recently pushed blocks looking for a thinking
    /// block that's still in `Streaming`. Stops at the current
    /// `TurnHeader` to avoid latching onto a thinking block from a
    /// previous turn after it was somehow left dangling.
    fn last_streaming_thinking_mut(&mut self) -> Option<&mut ThinkingBlock> {
        for b in self.blocks.iter_mut().rev() {
            match b {
                Block::Thinking(t) if matches!(t.state, ThinkingState::Streaming { .. }) => {
                    return Some(t);
                }
                Block::TurnHeader { .. } => return None,
                _ => continue,
            }
        }
        None
    }

    fn mark_orphan_thinking_incomplete(&mut self) {
        // A turn can carry several thinking blocks; we walk all the way
        // to `TurnHeader` and convert every still-Streaming one rather
        // than breaking on the first Finished hit (which is what the
        // tool-call equivalent does, since tool calls finalize in
        // submission order).
        for b in self.blocks.iter_mut().rev() {
            match b {
                Block::Thinking(t) => {
                    if let ThinkingState::Streaming { started_at } = t.state {
                        t.state = ThinkingState::Incomplete {
                            elapsed_secs: Some(started_at.elapsed().as_secs()),
                        };
                    }
                }
                Block::TurnHeader { .. } => break,
                _ => {}
            }
        }
    }

    fn last_streaming_compact_mut(&mut self) -> Option<&mut CompactEvent> {
        for b in self.blocks.iter_mut().rev() {
            match b {
                Block::Compact(evt) if matches!(evt, CompactEvent::Streaming { .. }) => {
                    return Some(evt);
                }
                Block::Compact(_) => return None,
                _ => continue,
            }
        }
        None
    }

    pub(crate) fn mark_orphan_compacts_incomplete(&mut self) {
        for b in self.blocks.iter_mut().rev() {
            if let Block::Compact(evt) = b {
                if let CompactEvent::Streaming { started_at } = evt {
                    *evt = CompactEvent::Incomplete {
                        elapsed_secs: Some(started_at.elapsed().as_secs()),
                    };
                } else {
                    break;
                }
            }
        }
    }

    fn find_tool_call_mut(&mut self, id: &str) -> Option<&mut ToolCallBlock> {
        for b in self.blocks.iter_mut().rev() {
            if let Block::ToolCall(tc) = b
                && tc.id == id
            {
                return Some(tc);
            }
        }
        None
    }

    /// Called on `TurnEnd`: mark any tool call still in an in-progress
    /// state as `Incomplete` so the user sees something was left hanging
    /// instead of a silently-truncated block.
    fn mark_orphan_tool_calls_incomplete(&mut self) {
        for b in self.blocks.iter_mut().rev() {
            if let Block::ToolCall(tc) = b {
                if matches!(
                    tc.state,
                    ToolCallState::Pending | ToolCallState::Streaming | ToolCallState::Executing
                ) {
                    tc.state = ToolCallState::Incomplete;
                } else {
                    // Earlier tool calls in the same list are already
                    // finalized; stop walking.
                    break;
                }
            } else if matches!(b, Block::TurnHeader { .. }) {
                break;
            }
        }
    }

    pub fn is_command_mode(&self) -> bool {
        self.input_mode == CommandInputMode::Command
    }

    pub fn enter_command_mode(&mut self) {
        self.input_mode = CommandInputMode::Command;
        self.completion = None;
        self.quit_confirm = None;
    }

    pub fn exit_command_mode(&mut self) {
        self.input_mode = CommandInputMode::Composer;
        self.command_input.clear();
    }

    pub fn clear_command_input(&mut self) {
        self.command_input.clear();
    }

    pub fn command_text(&self) -> String {
        self.command_input.plain_text()
    }

    pub fn command_suggestions(&self) -> Vec<crate::command::CommandCandidate> {
        self.command_registry.suggest(&self.command_text())
    }

    fn command_environment(&self) -> CommandEnvironment {
        CommandEnvironment {
            connected: self.connected,
            running: self.running,
            paused: self.paused,
        }
    }

    pub fn submit_command(&mut self) -> Option<Method> {
        let command_line = self.command_text();
        let environment = self.command_environment();
        let result = self.command_registry.dispatch(&command_line, &environment);
        self.apply_command_execution(result)
    }

    fn apply_command_execution(&mut self, result: CommandExecution) -> Option<Method> {
        for diagnostic in result.diagnostics {
            self.push_command_diagnostic(diagnostic.message);
        }
        if result.clear_input {
            self.command_input.clear();
        }
        if result.exit_command_mode {
            self.input_mode = CommandInputMode::Composer;
        }
        result.method
    }

    fn push_command_diagnostic(&mut self, message: impl Into<String>) {
        self.blocks.push(Block::Alert {
            level: AlertLevel::Warn,
            source: AlertSource::Pod,
            message: format!("TUI command: {}", message.into()),
        });
    }

    fn active_input_mut(&mut self) -> &mut InputBuffer {
        if self.is_command_mode() {
            &mut self.command_input
        } else {
            &mut self.input
        }
    }

    // Input manipulation — thin forwarders so call sites in main.rs
    // stay readable. In command mode these operate on the command line,
    // keeping the normal composer buffer intact.
    pub fn insert_char(&mut self, c: char) {
        self.active_input_mut().insert_char(c);
    }
    pub fn insert_newline(&mut self) {
        self.active_input_mut().insert_newline();
    }
    pub fn insert_paste(&mut self, content: String) {
        if self.is_command_mode() {
            self.command_input.insert_str(&content);
        } else {
            self.input.insert_paste(content);
        }
    }
    pub fn delete_char_before(&mut self) {
        self.active_input_mut().delete_before();
    }
    pub fn delete_char_after(&mut self) {
        self.active_input_mut().delete_after();
    }
    pub fn move_cursor_left(&mut self) {
        self.active_input_mut().move_left();
    }
    pub fn move_cursor_right(&mut self) {
        self.active_input_mut().move_right();
    }
    pub fn move_cursor_start(&mut self) {
        self.active_input_mut().move_start();
    }
    pub fn move_cursor_home(&mut self) {
        self.active_input_mut().move_home();
    }
    pub fn move_cursor_end(&mut self) {
        self.active_input_mut().move_end();
    }
    pub fn move_cursor_up(&mut self) {
        self.active_input_mut().move_up();
    }
    pub fn move_cursor_down(&mut self) {
        self.active_input_mut().move_down();
    }

    /// Reset the block list and replay a connect-time `Event::Snapshot`.
    ///
    /// Walks the session-log entries in commit order, expanding each
    /// LogEntry variant into the same blocks live events would have
    /// produced. Followed by `Event::Entry` updates for anything
    /// committed after the snapshot.
    fn restore_snapshot(&mut self, entries: &[serde_json::Value], greeting: protocol::Greeting) {
        self.context_window = greeting.context_window;
        self.session_context_tokens = greeting.context_tokens;
        self.turn_index = 0;
        self.blocks.clear();
        self.cache = FileCache::new();
        self.task_store = TaskStore::new();
        self.task_pane_scroll = 0;
        self.blocks.push(Block::Greeting(greeting));
        self.assistant_streaming = false;

        for entry in entries {
            self.apply_log_entry_raw(entry);
        }

        self.mark_orphan_tool_calls_incomplete_pass();
    }

    /// Drop the derived view in preparation for replaying a new
    /// `SegmentStart` (compaction / fork). Greeting is preserved
    /// because the Pod identity hasn't changed.
    fn reset_for_rotation(&mut self) {
        let greeting = self.blocks.iter().find_map(|b| match b {
            Block::Greeting(g) => Some(g.clone()),
            _ => None,
        });
        self.turn_index = 0;
        self.blocks.clear();
        self.cache = FileCache::new();
        self.task_store = TaskStore::new();
        self.task_pane_scroll = 0;
        if let Some(g) = greeting {
            self.blocks.push(Block::Greeting(g));
        }
    }

    /// Walk a single `LogEntry` JSON value and translate it into blocks
    /// the live event path would have produced. Shared between
    /// `restore_snapshot` (replay path) and `apply_log_entry` (live
    /// path).
    fn apply_log_entry_raw(&mut self, value: &serde_json::Value) {
        let Ok(entry) = serde_json::from_value::<session_store::LogEntry>(value.clone()) else {
            return;
        };
        match entry {
            session_store::LogEntry::SegmentStart { history, .. } => {
                for logged in history {
                    let item: llm_worker::Item = logged.into();
                    let item_value = serde_json::to_value(&item).expect("Item is Serialize");
                    self.push_history_item(&item_value);
                }
            }
            session_store::LogEntry::UserInput { segments, .. } => {
                self.turn_index += 1;
                self.blocks.push(Block::TurnHeader {
                    turn: self.turn_index,
                });
                if !segments.is_empty() {
                    self.blocks.push(Block::UserMessage { segments });
                }
            }
            session_store::LogEntry::AssistantItem { item, .. }
            | session_store::LogEntry::ToolResult { item, .. } => {
                let it: llm_worker::Item = item.into();
                let item_value = serde_json::to_value(&it).expect("Item is Serialize");
                self.push_history_item(&item_value);
            }
            session_store::LogEntry::SystemItem { item, .. } => {
                let value = serde_json::to_value(&item).expect("SystemItem is Serialize");
                self.apply_system_item(&value);
            }
            // Non-history-bearing variants don't affect the block view.
            _ => {}
        }
    }

    /// Dispatch one `SystemItem` JSON value into the appropriate block.
    ///
    /// Kind-based routing replaces the old free-text `[Notification]` /
    /// `[File: …]` parsing path: each kind maps directly to a typed
    /// block (`Block::Notify`, `Block::PodEvent`, …).
    fn apply_system_item(&mut self, value: &serde_json::Value) {
        let Ok(item) = serde_json::from_value::<session_store::SystemItem>(value.clone()) else {
            // Unknown / forward-compat shape: fall back to rendering the
            // raw text payload (if any) as a generic system message.
            if let Some(text) = value.get("body").and_then(|b| b.as_str()) {
                self.task_store.apply_system_message_text(text);
                self.blocks.push(Block::SystemMessage {
                    text: text.to_owned(),
                });
            }
            return;
        };
        match item {
            session_store::SystemItem::Notification { message, .. } => {
                self.blocks.push(Block::Notify { message });
            }
            session_store::SystemItem::PodEvent { event, .. } => {
                self.blocks.push(Block::PodEvent { event });
            }
            session_store::SystemItem::FileAttachment { body, .. }
            | session_store::SystemItem::Knowledge { body, .. }
            | session_store::SystemItem::Workflow { body, .. }
            | session_store::SystemItem::Interrupt { body } => {
                self.task_store.apply_system_message_text(&body);
                self.blocks.push(Block::SystemMessage { text: body });
            }
        }
    }

    /// Sweep all current tool-call blocks: any that never resolved into
    /// a Done / Error state get marked Incomplete. Called after a
    /// snapshot replay so dangling in-flight tool calls in the seed
    /// log match live semantics.
    fn mark_orphan_tool_calls_incomplete_pass(&mut self) {
        for b in self.blocks.iter_mut() {
            if let Block::ToolCall(tc) = b
                && matches!(
                    tc.state,
                    ToolCallState::Executing | ToolCallState::Pending | ToolCallState::Streaming
                )
            {
                tc.state = ToolCallState::Incomplete;
            }
        }
    }
}

pub fn fmt_tokens(n: u64) -> String {
    if n >= 1_000_000 {
        format!("{:.1}M", n as f64 / 1_000_000.0)
    } else if n >= 1_000 {
        format!("{:.1}k", n as f64 / 1_000.0)
    } else {
        n.to_string()
    }
}

fn message_text(item: &serde_json::Value) -> String {
    item["content"]
        .as_array()
        .map(|parts| {
            parts
                .iter()
                .filter_map(|p| p["text"].as_str())
                .collect::<Vec<_>>()
                .join("\n")
        })
        .unwrap_or_default()
}

/// Strip the `cat -n` line-number gutter that the Read tool prepends to
/// its output (one `"{n:>6}\t{content}"` per line) and return the raw
/// file body. Lines that don't match the pattern are kept verbatim, so
/// unrelated payloads pass through unharmed.
fn strip_cat_n_prefix(formatted: &str) -> String {
    let mut out = String::with_capacity(formatted.len());
    let mut first = true;
    for line in formatted.split('\n') {
        if !first {
            out.push('\n');
        }
        first = false;
        match line.split_once('\t') {
            Some((prefix, rest)) if prefix.trim().chars().all(|c| c.is_ascii_digit()) => {
                out.push_str(rest);
            }
            _ => out.push_str(line),
        }
    }
    out
}

fn rollback_input_preview(text: &str) -> String {
    const MAX_CHARS: usize = 80;
    let mut one_line = text.replace('\n', "⏎");
    if one_line.chars().count() > MAX_CHARS {
        one_line = one_line.chars().take(MAX_CHARS).collect::<String>();
        one_line.push('…');
    }
    one_line
}

/// True if the submitted segment list carries no user-visible content
/// (only whitespace / newlines, no paste, no typed atoms). Used to
/// decide whether an empty Enter should be a no-op or trigger a
/// `Resume` when the Pod is paused.
fn segments_are_blank(segments: &[Segment]) -> bool {
    segments.iter().all(|s| match s {
        Segment::Text { content } => content.trim().is_empty(),
        _ => false,
    })
}

pub fn alert_source_label(source: AlertSource) -> &'static str {
    match source {
        AlertSource::Pod => "pod",
        AlertSource::Worker => "worker",
        AlertSource::Compactor => "compactor",
        AlertSource::AgentsMd => "AGENTS.md",
    }
}

#[cfg(test)]
mod completion_flow_tests {
    use super::*;

    #[test]
    fn typing_at_creates_completion_state_and_emits_query() {
        let mut app = App::new("test".into());
        app.insert_char('@');
        let method = app.refresh_completion();
        match method {
            Some(Method::ListCompletions { kind, prefix }) => {
                assert_eq!(kind, CompletionKind::File);
                assert_eq!(prefix, "");
            }
            other => panic!("expected ListCompletions, got {other:?}"),
        }
        assert!(app.completion.is_some());
    }

    #[test]
    fn appending_to_token_emits_updated_query() {
        let mut app = App::new("test".into());
        app.insert_char('@');
        let _ = app.refresh_completion();
        app.insert_char('s');
        let method = app.refresh_completion();
        match method {
            Some(Method::ListCompletions { kind, prefix }) => {
                assert_eq!(kind, CompletionKind::File);
                assert_eq!(prefix, "s");
            }
            other => panic!("expected ListCompletions, got {other:?}"),
        }
    }

    #[test]
    fn space_after_token_clears_completion_state() {
        let mut app = App::new("test".into());
        for c in "@x".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        assert!(app.completion.is_some());
        app.insert_char(' ');
        let method = app.refresh_completion();
        assert!(method.is_none());
        assert!(app.completion.is_none());
    }

    #[test]
    fn tab_inserts_entry_value_as_text_for_file() {
        let mut app = App::new("test".into());
        for c in "@s".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "src/main.rs".into(),
            is_dir: false,
        }];
        // Tab path: text inserted, popup re-triggered with new prefix
        // (still File kind since the typed range stays after `@`).
        let _ = app.apply_completion_text();
        // The input now reads `@src/main.rs` as plain Char atoms; no
        // chip yet.
        let segs = app.input.submit_segments();
        assert_eq!(segs.len(), 1);
        assert!(matches!(&segs[0], Segment::Text { content } if content == "@src/main.rs"));
        assert!(app.completion.is_some());
    }

    #[test]
    fn tab_appends_trailing_slash_for_directory() {
        let mut app = App::new("test".into());
        for c in "@cr".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "crates".into(),
            is_dir: true,
        }];
        let _ = app.apply_completion_text();
        // Typed prefix advances to `crates/` so the next query can
        // descend into the directory.
        assert_eq!(app.completion.as_ref().unwrap().prefix, "crates/");
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::Text { content } if content == "@crates/"));
    }

    #[test]
    fn space_chipifies_on_exact_match() {
        let mut app = App::new("test".into());
        for c in "@src/main.rs".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "src/main.rs".into(),
            is_dir: false,
        }];
        assert!(app.chipify_completion_if_exact_match());
        assert!(app.completion.is_none());
        let segs = app.input.submit_segments();
        assert_eq!(segs.len(), 1);
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "src/main.rs"));
    }

    #[test]
    fn space_does_not_chipify_on_partial_match() {
        let mut app = App::new("test".into());
        for c in "@s".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "src/main.rs".into(),
            is_dir: false,
        }];
        // typed = "s", expected = "src/main.rs" → no match, no chip.
        assert!(!app.chipify_completion_if_exact_match());
        let segs = app.input.submit_segments();
        assert_eq!(segs.len(), 1);
        assert!(matches!(&segs[0], Segment::Text { content } if content == "@s"));
    }

    #[test]
    fn space_chipifies_directory_with_or_without_trailing_slash() {
        // Slash-less typed form chipifies the directory; the chip's
        // path keeps a trailing slash so the rendered label is `@crates/`.
        let mut app = App::new("test".into());
        for c in "@crates".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "crates".into(),
            is_dir: true,
        }];
        assert!(app.chipify_completion_if_exact_match());
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "crates/"));

        // Slashed typed form (the shape Tab inserts) — same chip.
        let mut app = App::new("test".into());
        for c in "@crates/".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "crates".into(),
            is_dir: true,
        }];
        assert!(app.chipify_completion_if_exact_match());
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "crates/"));
    }

    #[test]
    fn space_chipifies_directory_when_popup_shows_its_children() {
        // `@crates/` is the form Tab leaves you in after picking a
        // directory; the popup is showing the children of `crates/`.
        // Hitting space at this point should chipify `crates`, not
        // require the user to back up and remove the trailing slash.
        let mut app = App::new("test".into());
        for c in "@crates/".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![
            CompletionEntry {
                value: "crates/daemon".into(),
                is_dir: true,
            },
            CompletionEntry {
                value: "crates/llm-worker".into(),
                is_dir: true,
            },
        ];
        assert!(app.chipify_completion_if_exact_match());
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "crates/"));
    }

    #[test]
    fn enter_does_not_chipify_directory_so_drill_in_works() {
        // Enter on a selected directory entry must NOT chipify —
        // otherwise the user can never drill into the dir to see
        // its children.
        let mut app = App::new("test".into());
        for c in "@crates".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "crates".into(),
            is_dir: true,
        }];
        assert!(!app.chipify_selected_completion_if_committable());
        // Popup is still active so the caller can fall through to
        // apply_completion_text.
        assert!(app.completion.is_some());
    }

    #[test]
    fn enter_path_appends_trailing_space_after_file_chip() {
        // Mirrors the main.rs Enter handler sequence: chipify the
        // selected entry, then insert a space so the cursor is ready
        // for the next token without a manual separator.
        let mut app = App::new("test".into());
        for c in "@README.".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "README.md".into(),
            is_dir: false,
        }];
        assert!(app.chipify_selected_completion_if_committable());
        app.insert_char(' ');
        let segs = app.input.submit_segments();
        assert_eq!(segs.len(), 2);
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "README.md"));
        assert!(matches!(&segs[1], Segment::Text { content } if content == " "));
    }

    #[test]
    fn enter_chipifies_selected_file_even_when_typed_is_partial() {
        // Enter respects the selected entry: typed text may be a
        // prefix of the entry's value, but the popup-highlighted
        // file should still chipify on Enter.
        let mut app = App::new("test".into());
        for c in "@README.".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "README.md".into(),
            is_dir: false,
        }];
        assert!(app.chipify_selected_completion_if_committable());
        assert!(app.completion.is_none());
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "README.md"));
    }

    #[test]
    fn space_does_not_chipify_drilled_state_with_unrelated_entries() {
        // Stale entries that don't live under the typed prefix should
        // not satisfy the drilled-into-directory rule.
        let mut app = App::new("test".into());
        for c in "@xyz/".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![CompletionEntry {
            value: "crates/daemon".into(),
            is_dir: true,
        }];
        assert!(!app.chipify_completion_if_exact_match());
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::Text { content } if content == "@xyz/"));
    }

    #[test]
    fn chipify_finds_match_outside_selected_index() {
        // Regression guard for the race where a stale reply leaves a
        // non-matching entry at index 0 but an entry deeper in the
        // list does match the current typed text.
        let mut app = App::new("test".into());
        for c in "@src/main.rs".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        app.completion.as_mut().unwrap().entries = vec![
            CompletionEntry {
                value: "src/main.rs.bak".into(),
                is_dir: false,
            },
            CompletionEntry {
                value: "src/main.rs".into(),
                is_dir: false,
            },
        ];
        // selected stays at 0 (the non-matching one) but find() should
        // still locate the match.
        assert!(app.chipify_completion_if_exact_match());
        let segs = app.input.submit_segments();
        assert!(matches!(&segs[0], Segment::FileRef { path } if path == "src/main.rs"));
    }

    #[test]
    fn apply_completion_text_with_no_entries_is_a_noop() {
        let mut app = App::new("test".into());
        for c in "@x".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        // No `Event::Completions` arrived yet — entries is still empty.
        assert!(app.apply_completion_text().is_none());
        assert!(app.completion.is_some());
    }

    #[test]
    fn outdated_completions_event_is_dropped() {
        let mut app = App::new("test".into());
        for c in "@x".chars() {
            app.insert_char(c);
        }
        let _ = app.refresh_completion();
        // Reply for a different kind shouldn't overwrite state.
        app.handle_pod_event(Event::Completions {
            kind: CompletionKind::Workflow,
            entries: vec![CompletionEntry {
                value: "stale".into(),
                is_dir: false,
            }],
        });
        assert!(app.completion.as_ref().unwrap().entries.is_empty());
    }

    #[test]
    fn rolled_back_run_restores_input_and_removes_submit_blocks() {
        let mut app = App::new("test".into());
        let submitted = submit_text(&mut app, "please wait");
        assert_eq!(input_text(&app), "");

        app.handle_pod_event(Event::UserMessage {
            segments: submitted,
        });
        // Simulate run-derived attachment display after the submitted user line.
        app.blocks.push(Block::SystemMessage {
            text: "[File: README.md]".into(),
        });
        app.handle_pod_event(Event::TurnStart { turn: 1 });
        app.handle_pod_event(Event::Usage {
            input_tokens: Some(100),
            output_tokens: Some(0),
            cache_read_input_tokens: Some(40),
        });
        app.handle_pod_event(Event::RunEnd {
            result: RunResult::RolledBack,
        });

        assert_eq!(input_text(&app), "please wait");
        assert_eq!(app.turn_index, 0);
        assert!(app.blocks.iter().all(|b| !matches!(
            b,
            Block::TurnHeader { .. }
                | Block::UserMessage { .. }
                | Block::SystemMessage { .. }
                | Block::TurnStats { .. }
        )));
        assert!(warning_contains(&app, "restored your input"));
        assert!(matches!(app.pod_status, PodStatus::Idle));
        assert!(!app.running);
        assert!(!app.paused);
        assert_eq!(app.run_requests, 0);
        assert_eq!(app.run_upload_tokens, 0);
        assert_eq!(app.run_output_tokens, 0);
        assert!(app.current_tool.is_none());
    }

    #[test]
    fn rolled_back_run_does_not_overwrite_existing_unsent_input() {
        let mut app = App::new("test".into());
        let submitted = submit_text(&mut app, "original submit");
        app.handle_pod_event(Event::UserMessage {
            segments: submitted,
        });
        for c in "draft while running".chars() {
            app.insert_char(c);
        }

        app.handle_pod_event(Event::RunEnd {
            result: RunResult::RolledBack,
        });

        assert_eq!(input_text(&app), "draft while running");
        assert_eq!(
            Segment::flatten_to_text(app.last_rolled_back_input.as_ref().unwrap()),
            "original submit"
        );
        assert!(warning_contains(&app, "composer was not empty"));
        assert!(app.blocks.iter().all(|b| !matches!(
            b,
            Block::TurnHeader { .. } | Block::UserMessage { .. } | Block::TurnStats { .. }
        )));
    }

    #[test]
    fn non_rolled_back_run_end_keeps_submitted_blocks_and_does_not_restore_input() {
        for result in [RunResult::Paused, RunResult::Finished] {
            let mut app = App::new("test".into());
            let submitted = submit_text(&mut app, "normal run");
            app.handle_pod_event(Event::UserMessage {
                segments: submitted,
            });
            app.handle_pod_event(Event::RunEnd { result });

            assert_eq!(input_text(&app), "");
            assert!(
                app.blocks
                    .iter()
                    .any(|b| matches!(b, Block::TurnHeader { .. }))
            );
            assert!(
                app.blocks
                    .iter()
                    .any(|b| matches!(b, Block::UserMessage { .. }))
            );
            assert!(
                app.blocks
                    .iter()
                    .any(|b| matches!(b, Block::TurnStats { .. }))
            );
            assert!(!warning_contains(&app, "Rolled back empty assistant turn"));
            assert!(app.last_rolled_back_input.is_none());
        }
    }

    #[test]
    fn running_submit_is_queued_locally_and_clears_composer() {
        let mut app = App::new("test".into());
        app.set_pod_status(PodStatus::Running);
        insert_text(&mut app, "queued turn");

        assert!(app.submit_input().is_none());

        assert_eq!(app.queued_input_count(), 1);
        assert_eq!(app.next_queued_input_preview(), Some("queued turn"));
        assert_eq!(input_text(&app), "");
    }

    #[test]
    fn finished_run_auto_sends_next_queued_input() {
        let mut app = App::new("test".into());
        app.set_pod_status(PodStatus::Running);
        insert_text(&mut app, "next turn");
        assert!(app.submit_input().is_none());

        let method = app.handle_pod_event(Event::RunEnd {
            result: RunResult::Finished,
        });

        match method {
            Some(Method::Run { input }) => {
                assert_eq!(Segment::flatten_to_text(&input), "next turn");
            }
            other => panic!("expected queued Run, got {other:?}"),
        }
        assert_eq!(app.queued_input_count(), 0);
    }

    #[test]
    fn limit_reached_run_auto_sends_next_queued_input() {
        let mut app = App::new("test".into());
        app.set_pod_status(PodStatus::Running);
        insert_text(&mut app, "next after limit");
        assert!(app.submit_input().is_none());

        let method = app.handle_pod_event(Event::RunEnd {
            result: RunResult::LimitReached,
        });

        match method {
            Some(Method::Run { input }) => {
                assert_eq!(Segment::flatten_to_text(&input), "next after limit");
            }
            other => panic!("expected queued Run, got {other:?}"),
        }
        assert_eq!(app.queued_input_count(), 0);
    }

    #[test]
    fn paused_and_rolled_back_run_do_not_auto_send_queue() {
        for result in [RunResult::Paused, RunResult::RolledBack] {
            let mut app = App::new("test".into());
            app.set_pod_status(PodStatus::Running);
            insert_text(&mut app, "held turn");
            assert!(app.submit_input().is_none());

            let method = app.handle_pod_event(Event::RunEnd { result });

            assert!(method.is_none());
            assert_eq!(app.queued_input_count(), 1);
            assert_eq!(app.next_queued_input_preview(), Some("held turn"));
        }
    }

    #[test]
    fn paused_empty_submit_still_resumes_immediately() {
        let mut app = App::new("test".into());
        app.set_pod_status(PodStatus::Paused);

        assert!(matches!(app.submit_input(), Some(Method::Resume)));
        assert_eq!(app.queued_input_count(), 0);
    }

    #[test]
    fn queued_input_can_be_restored_to_composer_or_cleared() {
        let mut app = App::new("test".into());
        app.set_pod_status(PodStatus::Running);
        insert_text(&mut app, "edit me");
        assert!(app.submit_input().is_none());

        assert!(app.restore_next_queued_input_to_composer());
        assert_eq!(app.queued_input_count(), 0);
        assert_eq!(input_text(&app), "edit me");

        app.input.clear();
        insert_text(&mut app, "clear me");
        assert!(app.submit_input().is_none());
        assert_eq!(app.clear_queued_inputs(), 1);
        assert_eq!(app.queued_input_count(), 0);
    }

    fn insert_text(app: &mut App, text: &str) {
        for c in text.chars() {
            app.insert_char(c);
        }
    }

    fn submit_text(app: &mut App, text: &str) -> Vec<Segment> {
        for c in text.chars() {
            app.insert_char(c);
        }
        match app.submit_input() {
            Some(Method::Run { input }) => input,
            other => panic!("expected Run, got {other:?}"),
        }
    }

    fn input_text(app: &App) -> String {
        Segment::flatten_to_text(&app.input.submit_segments())
    }

    fn warning_contains(app: &App, needle: &str) -> bool {
        app.blocks.iter().any(|block| {
            matches!(
                block,
                Block::Alert {
                    level: AlertLevel::Warn,
                    message,
                    ..
                } if message.contains(needle)
            )
        })
    }

    #[test]
    fn snapshot_renders_system_message_block_from_session_start() {
        let mut app = App::new("test".into());
        let session_start = session_store::LogEntry::SegmentStart {
            ts: 1,
            session_id: uuid::Uuid::nil(),
            system_prompt: None,
            config: Default::default(),
            history: vec![session_store::LoggedItem::from(
                &llm_worker::Item::system_message("[File: src/main.rs]\nfn main() {}"),
            )],
            forked_from: None,
            compacted_from: None,
        };
        let session_start_value = serde_json::to_value(&session_start).unwrap();
        app.handle_pod_event(Event::Snapshot {
            greeting: test_greeting(),
            entries: vec![session_start_value],
            status: PodStatus::Running,
        });

        assert!(matches!(app.pod_status, PodStatus::Running));
        assert!(app.running);
        assert!(matches!(
            app.blocks.get(1),
            Some(Block::SystemMessage { text }) if text == "[File: src/main.rs]\nfn main() {}"
        ));
    }

    #[test]
    fn live_system_item_workflow_appends_system_message_block() {
        let mut app = App::new("test".into());
        let item = serde_json::json!({
            "kind": "workflow",
            "slug": "build",
            "body": "[Workflow /build]\nRun the build",
        });
        app.handle_pod_event(Event::SystemItem { item });

        assert!(matches!(
            app.blocks.as_slice(),
            [Block::SystemMessage { text }] if text == "[Workflow /build]\nRun the build"
        ));
    }

    #[test]
    fn live_system_item_notification_appends_notify_block() {
        let mut app = App::new("test".into());
        let item = serde_json::json!({
            "kind": "notification",
            "message": "hi",
            "body": "[Notification] hi",
        });
        app.handle_pod_event(Event::SystemItem { item });
        assert!(matches!(
            app.blocks.as_slice(),
            [Block::Notify { message }] if message == "hi"
        ));
    }

    #[test]
    fn live_system_item_pod_event_appends_pod_event_block() {
        let mut app = App::new("test".into());
        let item = serde_json::json!({
            "kind": "pod_event",
            "event": { "kind": "turn_ended", "pod_name": "child" },
            "body": "[Notification] pod `child` finished a turn",
        });
        app.handle_pod_event(Event::SystemItem { item });
        assert_eq!(app.blocks.len(), 1);
        match &app.blocks[0] {
            Block::PodEvent {
                event: protocol::PodEvent::TurnEnded { pod_name },
            } => assert_eq!(pod_name, "child"),
            _ => panic!("expected a PodEvent block"),
        }
    }

    #[test]
    fn compact_done_replaces_live_block() {
        let mut app = App::new("test".into());
        let id = uuid::Uuid::parse_str("12345678-1234-5678-1234-567812345678").unwrap();

        app.handle_pod_event(Event::CompactStart);
        app.handle_pod_event(Event::CompactDone { new_segment_id: id });

        assert_eq!(compact_block_count(&app), 1);
        assert!(matches!(
            app.blocks.as_slice(),
            [Block::Compact(CompactEvent::Done {
                new_segment_id,
                elapsed_secs: Some(_),
            })] if *new_segment_id == id
        ));
    }

    #[test]
    fn compact_failed_replaces_live_block() {
        let mut app = App::new("test".into());

        app.handle_pod_event(Event::CompactStart);
        app.handle_pod_event(Event::CompactFailed {
            error: "provider 429".into(),
        });

        assert_eq!(compact_block_count(&app), 1);
        assert!(matches!(
            app.blocks.as_slice(),
            [Block::Compact(CompactEvent::Failed {
                error,
                elapsed_secs: Some(_),
            })] if error == "provider 429"
        ));
    }

    #[test]
    fn shutdown_marks_live_compact_incomplete() {
        let mut app = App::new("test".into());

        app.handle_pod_event(Event::CompactStart);
        app.handle_pod_event(Event::Shutdown);

        assert!(app.quit);
        assert!(matches!(
            app.blocks.as_slice(),
            [Block::Compact(CompactEvent::Incomplete {
                elapsed_secs: Some(_),
            })]
        ));
    }

    fn compact_block_count(app: &App) -> usize {
        app.blocks
            .iter()
            .filter(|block| matches!(block, Block::Compact(_)))
            .count()
    }

    fn test_greeting() -> protocol::Greeting {
        protocol::Greeting {
            pod_name: "test".into(),
            cwd: "/tmp".into(),
            provider: "test-provider".into(),
            model: "test-model".into(),
            scope_summary: String::new(),
            tools: Vec::new(),
            context_window: 200_000,
            context_tokens: 0,
        }
    }

    #[test]
    fn snapshot_initializes_context_usage() {
        let mut app = App::new("test".into());
        let mut greeting = test_greeting();
        greeting.context_window = 123_000;
        greeting.context_tokens = 45_000;

        app.handle_pod_event(Event::Snapshot {
            entries: Vec::new(),
            greeting,
            status: PodStatus::Idle,
        });

        assert_eq!(app.context_window, 123_000);
        assert_eq!(app.session_context_tokens, 45_000);
    }

    #[test]
    fn usage_updates_session_context_tokens_without_cache_discount() {
        let mut app = App::new("test".into());

        app.handle_pod_event(Event::Usage {
            input_tokens: Some(42_000),
            output_tokens: Some(9),
            cache_read_input_tokens: Some(40_000),
        });

        assert_eq!(app.session_context_tokens, 42_000);
        assert_eq!(app.run_upload_tokens, 2_000);
        assert_eq!(app.run_output_tokens, 9);
    }

    #[test]
    fn compact_done_resets_session_context_tokens() {
        let mut app = App::new("test".into());
        app.session_context_tokens = 42_000;

        app.handle_pod_event(Event::CompactDone {
            new_segment_id: uuid::Uuid::nil(),
        });

        assert_eq!(app.session_context_tokens, 0);
    }

    #[test]
    fn turn_start_and_run_end_do_not_reset_session_context_tokens() {
        let mut app = App::new("test".into());
        app.session_context_tokens = 42_000;

        app.handle_pod_event(Event::TurnStart { turn: 1 });
        app.handle_pod_event(Event::RunEnd {
            result: RunResult::Finished,
        });

        assert_eq!(app.session_context_tokens, 42_000);
    }

    #[test]
    fn live_task_create_updates_task_store() {
        let mut app = App::new("test".into());
        app.handle_pod_event(Event::ToolCallStart {
            id: "c1".into(),
            name: "TaskCreate".into(),
        });
        app.handle_pod_event(Event::ToolCallDone {
            id: "c1".into(),
            name: "TaskCreate".into(),
            arguments: r#"{"subject":"impl tasks","description":"do it"}"#.into(),
        });
        let tasks = app.task_store.tasks();
        assert_eq!(tasks.len(), 1);
        assert_eq!(tasks[0].subject, "impl tasks");
        assert_eq!(tasks[0].status, crate::task::TaskStatus::Pending);
    }

    #[test]
    fn live_task_update_advances_status() {
        let mut app = App::new("test".into());
        for (id, args) in [
            ("c1", r#"{"subject":"a","description":"A"}"#),
            ("u1", r#"{"taskid":1,"status":"completed"}"#),
        ] {
            let name = if id.starts_with('c') {
                "TaskCreate"
            } else {
                "TaskUpdate"
            };
            app.handle_pod_event(Event::ToolCallStart {
                id: id.into(),
                name: name.into(),
            });
            app.handle_pod_event(Event::ToolCallDone {
                id: id.into(),
                name: name.into(),
                arguments: args.into(),
            });
        }
        assert_eq!(
            app.task_store.tasks()[0].status,
            crate::task::TaskStatus::Completed
        );
    }

    #[test]
    fn live_system_snapshot_replaces_task_store() {
        let mut app = App::new("test".into());
        // Stale entry that the snapshot must wipe out.
        app.handle_pod_event(Event::ToolCallStart {
            id: "c1".into(),
            name: "TaskCreate".into(),
        });
        app.handle_pod_event(Event::ToolCallDone {
            id: "c1".into(),
            name: "TaskCreate".into(),
            arguments: r#"{"subject":"stale","description":""}"#.into(),
        });

        let snapshot = "[Session TaskStore snapshot]\n\n\
            TaskStore: 1 task(s)\n\n\
            ```json\n{\n  \"tasks\": [\n    {\n      \"taskid\": 4,\n      \
            \"status\": \"inprogress\",\n      \"subject\": \"from snapshot\",\n      \
            \"description\": \"d\"\n    }\n  ]\n}\n```\n";
        // Snapshot text injected as a workflow body (kind doesn't matter
        // for task-store parsing, only the text contents do).
        app.handle_pod_event(Event::SystemItem {
            item: serde_json::json!({
                "kind": "workflow",
                "slug": "task-snapshot",
                "body": snapshot,
            }),
        });

        let tasks = app.task_store.tasks();
        assert_eq!(tasks.len(), 1);
        assert_eq!(tasks[0].taskid, 4);
        assert_eq!(tasks[0].subject, "from snapshot");
    }

    #[test]
    fn snapshot_reconstructs_task_store() {
        let mut app = App::new("test".into());
        // Live tool call before the snapshot lands — restore must wipe
        // this so it doesn't double-count after replay.
        app.handle_pod_event(Event::ToolCallStart {
            id: "live".into(),
            name: "TaskCreate".into(),
        });
        app.handle_pod_event(Event::ToolCallDone {
            id: "live".into(),
            name: "TaskCreate".into(),
            arguments: r#"{"subject":"live","description":""}"#.into(),
        });

        let assistant_item_entries = vec![
            serde_json::json!({
                "kind": "assistant_item",
                "ts": 1,
                "item": {
                    "kind": "tool_call",
                    "call_id": "c1",
                    "name": "TaskCreate",
                    "arguments": r#"{"subject":"a","description":"A"}"#,
                },
            }),
            serde_json::json!({
                "kind": "assistant_item",
                "ts": 2,
                "item": {
                    "kind": "tool_call",
                    "call_id": "c2",
                    "name": "TaskCreate",
                    "arguments": r#"{"subject":"b","description":"B"}"#,
                },
            }),
            serde_json::json!({
                "kind": "assistant_item",
                "ts": 3,
                "item": {
                    "kind": "tool_call",
                    "call_id": "u1",
                    "name": "TaskUpdate",
                    "arguments": r#"{"taskid":2,"status":"inprogress"}"#,
                },
            }),
        ];
        app.handle_pod_event(Event::Snapshot {
            greeting: test_greeting(),
            entries: assistant_item_entries,
            status: PodStatus::Running,
        });

        let tasks = app.task_store.tasks();
        assert_eq!(tasks.len(), 2);
        assert_eq!(tasks[0].subject, "a");
        assert_eq!(tasks[1].subject, "b");
        assert_eq!(tasks[1].status, crate::task::TaskStatus::Inprogress);
    }

    #[test]
    fn task_pane_toggle_flips_state_and_resets_scroll() {
        let mut app = App::new("test".into());
        app.task_pane_scroll = 7;
        assert!(!app.task_pane_open);
        app.toggle_task_pane();
        assert!(app.task_pane_open);
        // Scroll position is preserved on open so the user keeps their
        // place if they re-open after closing.
        assert_eq!(app.task_pane_scroll, 7);
        app.toggle_task_pane();
        assert!(!app.task_pane_open);
        assert_eq!(app.task_pane_scroll, 0);
    }
}

/// Seed / mutate the file-content cache based on a completed tool call.
///
/// Each built-in file tool has its own rule: Read copies the result body
/// into the cache, Write replaces it with `args.content`, Edit applies
/// the `old_string → new_string` swap in-place.
fn apply_cache_update(
    cache: &mut FileCache,
    name: &str,
    arguments: Option<&str>,
    output: Option<&str>,
) {
    let args = arguments.and_then(|s| serde_json::from_str::<serde_json::Value>(s).ok());
    match name {
        "Read" => {
            let Some(args) = args.as_ref() else { return };
            let Some(path) = args["file_path"].as_str() else {
                return;
            };
            if let Some(content) = output {
                // The Read tool emits a `cat -n` style display: each
                // line is "{lineno:>6}\tcontent". Strip that framing
                // so the cache mirrors the real file body and the
                // Edit diff renderer has a faithful "before" view.
                cache.put(path, strip_cat_n_prefix(content));
            }
        }
        "Write" => {
            let Some(args) = args.as_ref() else { return };
            let Some(path) = args["file_path"].as_str() else {
                return;
            };
            let Some(content) = args["content"].as_str() else {
                return;
            };
            cache.put(path, content.to_owned());
        }
        "Edit" => {
            let Some(args) = args.as_ref() else { return };
            let Some(path) = args["file_path"].as_str() else {
                return;
            };
            let Some(old) = args["old_string"].as_str() else {
                return;
            };
            let Some(new) = args["new_string"].as_str() else {
                return;
            };
            cache.apply_edit(path, old, new);
        }
        _ => {}
    }
}