fix(chat): read Copilot tool outputs at verified record offsets

changelog.d/copilot-recent-tool-output.md

@@ -0,0 +1,2 @@
+### Fixed
+- Copilot chat can open older and recent tool results even after a transcript grows beyond 32 MiB.

server/conversation.ts

@@ -58,7 +58,7 @@ import { AgyUnavailable, agyCatalog, agyToolOutput, forgetAgyState, parseAgyTran
 import { resolveAgyStore, sameAgyStore, type AgyStore } from "./agy-store.ts";
 import { withinRetentionBudget } from "./retention-budget.ts";
 import { forgetAllPiIndexes, forgetPiIndex, piAbandonedTurns, piBranchRecords, piBranchSegments } from "./pi-tree.ts";
-import { copilotOutput, copilotRootRecord, parseCopilotTranscript } from "./copilot.ts";
+import { copilotOffsetOutput, copilotOutput, copilotRootRecord, parseCopilotTranscript } from "./copilot.ts";
 import { copilotExplicitResume, copilotProcessSession, copilotTranscriptFile, copilotUnwrittenSession, openCopilotFile } from "./copilot-store.ts";
 import { parseConversationMetadata } from "./conversation-metadata.ts";
 import { answerVersion, ConversationNotStarted, ConversationUnavailable, type ConversationPage, HistoryChanged, type RecognizedConversation, type StreamSource, TRANSCRIPT_WINDOW_BYTES } from "./conversation-shared.ts";
@@ -111,6 +111,16 @@ function copilotPrefix(paneId: string, identity: string): string {
   return prefix;
 }
 
+function copilotHistoryIdentity(path: string): string {
+  try {
+    const fd = openCopilotFile(path);
+    try {
+      const stat = fstatSync(fd);
+      return `${stat.dev}:${stat.ino}${transcriptGeneration(path, stat)}`;
+    } finally { closeSync(fd); }
+  } catch { throw new ConversationUnavailable("transcript_missing"); }
+}
+
 function copilotPage(page: ConversationPage, prefix: string): ConversationPage {
   const unbind = (cursor?: string): string | undefined => {
     if (cursor === undefined) return undefined;
@@ -486,8 +496,8 @@ function subagentsOnPage(path: string, text: string): ReadonlyMap<string, Subage
   return ids.size === 0 ? undefined : subagentDetails(path, ids);
 }
 
-function parseTurns(source: RecognizedConversation["source"], path: string, text: string, taskTitles?: Map<string, string>, noticed?: Set<string>): ConversationTurn[] {
-  if (source === "copilot-transcript") return parseCopilotTranscript(text, Infinity);
+function parseTurns(source: RecognizedConversation["source"], path: string, text: string, taskTitles?: Map<string, string>, noticed?: Set<string>, baseOffset?: number): ConversationTurn[] {
+  if (source === "copilot-transcript") return parseCopilotTranscript(text, Infinity, baseOffset);
   if (source === "grok-transcript") {
     try { return parseGrokTranscript(text, path); } catch (error) {
       if (error instanceof GrokUnavailable) throw new ConversationUnavailable("transcript_missing");
@@ -635,14 +645,14 @@ function liveTurns(path: string, stream: TranscriptStream, source: RecognizedCon
     if (kept !== undefined) {
       const from = kept.end <= start ? kept.end : kept.start;
       const to = Math.min(start, kept.observedEnd);
-      if (to > from) parseTurns(source, path, readStream(stream, from, to).toString("utf8"), inherited);
+      if (to > from) parseTurns(source, path, readStream(stream, from, to).toString("utf8"), inherited, undefined, from);
     }
     settled = { source, id: stream.id, start, end: start, turns: [], metadata: parseConversationMetadata(`${head}
 `, source, undefined, piAgentDir), tail: bytesBefore(stream, start), taskTitles: new Map(inherited), noticed: new Set(), inherited, observedEnd: stream.length, piAgentDir };
   }
   if (settled.end < last) {
     const text = readStream(stream, settled.end, last).toString("utf8");
-    settled = { ...settled, end: last, turns: [...settled.turns, ...parseTurns(source, path, text, settled.taskTitles, settled.noticed)], metadata: parseConversationMetadata(text, source, settled.metadata, piAgentDir), tail: bytesBefore(stream, last) };
+    settled = { ...settled, end: last, turns: [...settled.turns, ...parseTurns(source, path, text, settled.taskTitles, settled.noticed, settled.end)], metadata: parseConversationMetadata(text, source, settled.metadata, piAgentDir), tail: bytesBefore(stream, last) };
   }
   settled.observedEnd = stream.length;
   rememberPage(settledTurns, key, settled, 8);
@@ -653,7 +663,7 @@ function liveTurns(path: string, stream: TranscriptStream, source: RecognizedCon
   const text = readStream(stream, last, stream.length).toString("utf8");
   // the live turn is parsed again on every poll: its titles and completions are kept only
   // once it settles, so a read titles a task exactly as a cold read of the same bytes does
-  return { turns: [...settled.turns, ...parseTurns(source, path, text, new Map(settled.taskTitles), new Set(settled.noticed))], metadata: parseConversationMetadata(text, source, settled.metadata, piAgentDir) };
+  return { turns: [...settled.turns, ...parseTurns(source, path, text, new Map(settled.taskTitles), new Set(settled.noticed), last)], metadata: parseConversationMetadata(text, source, settled.metadata, piAgentDir) };
 }
 
 /** Retention diagnostics only: counts/budget adherence, never transcript contents. */
@@ -1315,7 +1325,8 @@ export async function paneConversation(paneId: string, codexHome?: string, page:
     : resolved.source === "claude-transcript" ? nodePath.basename(resolved.path, ".jsonl")
     : resolved.source === "pi-transcript" || resolved.source === "cmd-transcript" || resolved.source === "omp-transcript" ? realpathSync(resolved.path) : null;
   rememberPaneRead(paneId, resolved.path);
-  const prefix = resolved.source === "copilot-transcript" ? copilotPrefix(paneId, resolved.binding) : null;
+  const history = resolved.source === "copilot-transcript" ? copilotHistoryIdentity(resolved.path) : null;
+  const prefix = history !== null && resolved.source === "copilot-transcript" ? copilotPrefix(paneId, `${resolved.binding}\0${history}`) : null;
   const answer = transcriptPage(resolved.source, resolved.path, prefix === null ? page : copilotPage(page, prefix), resolved.codexHome ?? codexHome, resolved.piAgentDir);
   const status = snapshot.panes.find((pane) => pane.pane_id === paneId)?.agent_status;
   if (resolved.source === "grok-transcript" && answer.turns.length === 0 && page.before === undefined
@@ -1345,7 +1356,8 @@ export async function paneConversation(paneId: string, codexHome?: string, page:
   if (prefix !== null && resolved.source === "copilot-transcript") {
     const pane = snapshot.panes.find((candidate) => candidate.pane_id === paneId)!;
     const current = await copilotTranscriptPath(pane, snapshot.panes, resolved.peerClaims);
-    if (current.path !== resolved.path || current.binding !== resolved.binding) throw new HistoryChanged();
+    if (current.path !== resolved.path || current.binding !== resolved.binding
+      || copilotHistoryIdentity(resolved.path) !== history) throw new HistoryChanged();
     return bindCopilotAnswer(answer, prefix);
   }
   return answer;
@@ -1586,7 +1598,7 @@ function transcriptPageRead(source: StreamSource, path: string, page: Conversati
   // the store decides the parser, not the pane's label: omo writes omp's
   // session shape while herdr may be calling that same pane `claude`. The page
   // bounds the turns, so none are cut: they must meet the next page exactly.
-  const turns = live?.turns ?? parseTurns(source, path, text);
+  const turns = live?.turns ?? parseTurns(source, path, text, undefined, undefined, start);
   const metadata = live?.metadata ?? parseConversationMetadata(`${head}\n${text}`, source, undefined, piAgentDir);
   // Record the stat from BEFORE the read: an append during parsing must cause
   // another read on the next poll, not permanently cache a torn tail.
@@ -1894,7 +1906,7 @@ const TOOL_OUTPUT_MAX = 2_000_000;
 
 /** The whole output of a tool call whose page output was cut, by its id; null when there is none. */
 export async function toolOutput(paneId: string, ref: string, codexHome?: string, opencodeDb?: string, hermesHome?: string, grokHome?: string): Promise<string | null> {
-  if (!TOOL_REF.test(ref) && !/^cp[0-9a-f]{16}\.[A-Za-z0-9_:.-]{1,128}$/.test(ref)) return null;
+  if (!TOOL_REF.test(ref) && !/^cp[0-9a-f]{16}\.[A-Za-z0-9_:.-]{1,128}(?:@[0-9a-z]+@[0-9a-z]+@[0-9a-f]{32})?$/.test(ref)) return null;
   const snapshot = await sessionSnapshot();
   const pane = snapshot.panes.find((candidate) => candidate.pane_id === paneId);
   if (pane === undefined || typeof pane.cwd !== "string" || pane.cwd.length === 0) return null;
@@ -1909,22 +1921,28 @@ export async function toolOutput(paneId: string, ref: string, codexHome?: string
   if (resolved.source === "hermes-transcript") return hermesToolOutput(resolved.sessionId, resolved.path, ref, TOOL_OUTPUT_MAX);
   let nativeRef = ref;
   if (resolved.source === "copilot-transcript") {
-    const prefix = copilotPrefix(paneId, resolved.binding);
+    let history: string;
+    try { history = copilotHistoryIdentity(resolved.path); } catch { return null; }
+    const prefix = copilotPrefix(paneId, `${resolved.binding}\0${history}`);
     if (!ref.startsWith(prefix)) return null;
     nativeRef = ref.slice(prefix.length);
+    if (!nativeRef.includes("@")) return null;
   }
   const output = transcriptToolOutput(resolved.source, resolved.path, nativeRef, resolved.codexHome ?? codexHome);
   if (resolved.agy && !sameAgyStore(resolved.agy, await resolveAgyStore(pane))) return null;
   if (resolved.source === "copilot-transcript") {
     const current = await copilotTranscriptPath(pane, snapshot.panes, resolved.peerClaims).catch(() => null);
     if (current?.path !== resolved.path || current.binding !== resolved.binding) return null;
+    try {
+      if (!ref.startsWith(copilotPrefix(paneId, `${resolved.binding}\0${copilotHistoryIdentity(resolved.path)}`))) return null;
+    } catch { return null; }
   }
   return output;
 }
 
 /** The output a transcript file holds for one tool call id, whole (up to TOOL_OUTPUT_MAX). */
 export function transcriptToolOutput(source: StreamSource, path: string, ref: string, codexHome?: string): string | null {
-  if (!TOOL_REF.test(ref)) return null;
+  if (!TOOL_REF.test(ref) && !(source === "copilot-transcript" && /^[A-Za-z0-9_:.-]{1,128}@[0-9a-z]+@[0-9a-z]+@[0-9a-f]{32}$/.test(ref))) return null;
   if (source === "codex-transcript") {
     let segments: ReturnType<typeof codexHistorySegments>;
     try { segments = codexHistorySegments(path, codexHome); } catch { return null; }
@@ -1944,7 +1962,7 @@ export function transcriptToolOutput(source: StreamSource, path: string, ref: st
     let fd: number;
     try { fd = openCopilotFile(path); } catch { return null; }
     try {
-      return copilotOutput(fd, ref, TOOL_OUTPUT_MAX);
+      return ref.includes("@") ? copilotOffsetOutput(fd, ref, TOOL_OUTPUT_MAX) : copilotOutput(fd, ref, TOOL_OUTPUT_MAX);
     } finally { closeSync(fd); }
   }
   let text: string;

server/copilot.contract.test.ts

@@ -131,8 +131,9 @@ it.skipIf(process.platform !== "linux")("binds only the reported UUID to the for
   if (completed?.kind !== "tool" || !completed.output_ref) throw new Error("fixture tool output ref missing");
   const completedRef = completed.output_ref;
   expect(completed).toMatchObject({ kind: "tool", error: true });
-  expect(completedRef).toMatch(/^cp[0-9a-f]{16}\.call-1$/);
+  expect(completedRef).toMatch(/^cp[0-9a-f]{16}\.call-1@[0-9a-z]+@[0-9a-z]+@[0-9a-f]{32}$/);
   expect((await fetch(toolUrl("call-1"))).status).toBe(404);
+  expect((await fetch(toolUrl(completedRef.slice(0, completedRef.indexOf("@"))))).status).toBe(404);
   expect(await (await fetch(toolUrl(completedRef))).text()).toBe("error ".repeat(900));
   appendFileSync(file(id), event("session.resume", { selectedModel: "fixture-model" }) + event("user.message", { content: "appended" }));
   expect((await read()).history_id).toBe(first.history_id);