fix(session): reconcile compaction summary with preserved tail

packages/opencode/src/session/compaction.ts

@@ -37,6 +37,8 @@ export const Event = {
 export const PRUNE_MINIMUM = 20_000
 export const PRUNE_PROTECT = 40_000
 const TOOL_OUTPUT_MAX_CHARS = 2_000
+const RECENT_TAIL_AUDIT_MAX_CHARS = 4_000
+const RECENT_TAIL_AUDIT_PART_MAX_CHARS = 1_000
 const PRUNE_PROTECTED_TOOLS = ["skill"]
 const DEFAULT_TAIL_TURNS = 2
 const MIN_PRESERVE_RECENT_TOKENS = 2_000
@@ -63,7 +65,7 @@ const SUMMARY_TEMPLATE = `Output exactly the Markdown structure shown inside <te
 - [decision and why, or "(none)"]
 
 ## Next Steps
-- [ordered next actions or "(none)"]
+- [ordered unfinished future actions or "(none)"]
 
 ## Critical Context
 - [important technical facts, errors, open questions, or "(none)"]
@@ -76,6 +78,8 @@ Rules:
 - Keep every section, even when empty.
 - Use terse bullets, not prose paragraphs.
 - Preserve exact file paths, commands, error strings, and identifiers when known.
+- Next Steps must contain only unfinished future actions.
+- If recent preserved-tail audit says a task was completed, move it out of Next Steps.
 - Do not mention the summary process or that context was compacted.`
 type Turn = {
   start: number
@@ -122,7 +126,7 @@ function completedCompactions(messages: MessageV2.WithParts[]) {
   })
 }
 
-function buildPrompt(input: { previousSummary?: string; context: string[] }) {
+function buildPrompt(input: { previousSummary?: string; context: string[]; tail: MessageV2.WithParts[] }) {
   const anchor = input.previousSummary
     ? [
         "Update the anchored summary below using the conversation history above.",
@@ -132,7 +136,40 @@ function buildPrompt(input: { previousSummary?: string; context: string[] }) {
         "</previous-summary>",
       ].join("\n")
     : "Create a new anchored summary from the conversation history above."
-  return [anchor, SUMMARY_TEMPLATE, ...input.context].join("\n\n")
+  return [anchor, SUMMARY_TEMPLATE, recentTailAudit(input.tail), ...input.context].filter(Boolean).join("\n\n")
+}
+
+function recentTailAudit(messages: MessageV2.WithParts[]) {
+  const text = messages
+    .flatMap((msg) => {
+      const parts = msg.parts
+        .flatMap(recentTailPartText)
+        .map((part) => truncate(part.trim(), RECENT_TAIL_AUDIT_PART_MAX_CHARS))
+        .filter(Boolean)
+      if (!parts.length) return []
+      return [`### ${msg.info.role}\n${parts.join("\n")}`]
+    })
+    .join("\n\n")
+  if (!text) return undefined
+  return [
+    "<recent-preserved-tail-audit>",
+    "Use this text-only view only to reconcile Done, In Progress, Blocked, and Next Steps. Do not copy it wholesale into the summary.",
+    truncate(text, RECENT_TAIL_AUDIT_MAX_CHARS),
+    "</recent-preserved-tail-audit>",
+  ].join("\n")
+}
+
+function recentTailPartText(part: MessageV2.Part) {
+  if (part.type === "text") return [part.text]
+  if (part.type !== "tool") return []
+  if (part.state.status === "completed") return [`tool:${part.tool}\n${part.state.title}\n${part.state.output}`]
+  if (part.state.status === "error") return [`tool:${part.tool} error\n${part.state.error}`]
+  return []
+}
+
+function truncate(text: string, max: number) {
+  if (text.length <= max) return text
+  return `${text.slice(0, max).trimEnd()}\n[truncated]`
 }
 
 function preserveRecentBudget(input: { cfg: Config.Info; model: Provider.Model }) {
@@ -250,10 +287,10 @@ export const layer = Layer.effect(
       model: Provider.Model
     }) {
       const limit = input.cfg.compaction?.tail_turns ?? DEFAULT_TAIL_TURNS
-      if (limit <= 0) return { head: input.messages, tail_start_id: undefined }
+      if (limit <= 0) return { head: input.messages, tail: [], tail_start_id: undefined }
       const budget = preserveRecentBudget({ cfg: input.cfg, model: input.model })
       const all = turns(input.messages)
-      if (!all.length) return { head: input.messages, tail_start_id: undefined }
+      if (!all.length) return { head: input.messages, tail: [], tail_start_id: undefined }
       const recent = all.slice(-limit)
       const sizes = yield* Effect.forEach(
         recent,
@@ -288,9 +325,10 @@ export const layer = Layer.effect(
         break
       }
 
-      if (!keep || keep.start === 0) return { head: input.messages, tail_start_id: undefined }
+      if (!keep || keep.start === 0) return { head: input.messages, tail: [], tail_start_id: undefined }
       return {
         head: input.messages.slice(0, keep.start),
+        tail: input.messages.slice(keep.start),
         tail_start_id: keep.id,
       }
     })
@@ -402,7 +440,7 @@ export const layer = Layer.effect(
         { sessionID: input.sessionID },
         { context: [], prompt: undefined },
       )
-      const nextPrompt = compacting.prompt ?? buildPrompt({ previousSummary, context: compacting.context })
+      const nextPrompt = compacting.prompt ?? buildPrompt({ previousSummary, context: compacting.context, tail: selected.tail })
       const msgs = structuredClone(selected.head)
       yield* plugin.trigger("experimental.chat.messages.transform", {}, { messages: msgs })
       const modelMessages = yield* MessageV2.toModelMessagesEffect(msgs, model, {

packages/opencode/test/session/compaction.test.ts

@@ -1052,8 +1052,14 @@ describe("session.compaction.process", () => {
     "retains a split turn suffix when a later message fits the preserve token budget",
     () => {
       const stub = llm()
-      let captured = ""
-      stub.push(reply("summary", (input) => (captured = JSON.stringify(input.messages))))
+      let history = ""
+      let prompt = ""
+      stub.push(
+        reply("summary", (input) => {
+          history = JSON.stringify(input.messages.slice(0, -1))
+          prompt = JSON.stringify(input.messages.at(-1))
+        }),
+      )
       return Effect.gen(function* () {
         const test = yield* TestInstance
         const ssn = yield* SessionNs.Service
@@ -1086,8 +1092,9 @@ describe("session.compaction.process", () => {
         const part = yield* readCompactionPart(session.id)
         expect(part?.type).toBe("compaction")
         expect(part?.tail_start_id).toBe(keep.id)
-        expect(captured).toContain("zzzz")
-        expect(captured).not.toContain("keep tail")
+        expect(history).toContain("zzzz")
+        expect(history).not.toContain("keep tail")
+        expect(prompt).toContain("keep tail")
 
         const filtered = MessageV2.filterCompacted(MessageV2.stream(session.id))
         expect(filtered.map((msg) => msg.info.id).slice(0, 3)).toEqual([parent!, expect.any(String), keep.id])
@@ -1363,10 +1370,12 @@ describe("session.compaction.process", () => {
     "summarizes only the head while keeping recent tail out of summary input",
     () => {
       const stub = llm()
-      let captured = ""
+      let history = ""
+      let prompt = ""
       stub.push(
         reply("summary", (input) => {
-          captured = JSON.stringify(input.messages)
+          history = JSON.stringify(input.messages.slice(0, -1))
+          prompt = JSON.stringify(input.messages.at(-1))
         }),
       )
       return Effect.gen(function* () {
@@ -1387,15 +1396,89 @@ describe("session.compaction.process", () => {
           auto: false,
         })
 
-        expect(captured).toContain("older context")
-        expect(captured).not.toContain("keep this turn")
-        expect(captured).not.toContain("and this one too")
-        expect(captured).not.toContain("What did we do so far?")
+        expect(history).toContain("older context")
+        expect(history).not.toContain("keep this turn")
+        expect(history).not.toContain("and this one too")
+        expect(prompt).toContain("<recent-preserved-tail-audit>")
+        expect(prompt).toContain("keep this turn")
+        expect(prompt).toContain("and this one too")
+        expect(`${history}${prompt}`).not.toContain("What did we do so far?")
       }).pipe(withCompaction({ llm: stub.layer }))
     },
     { git: true },
   )
 
+  itCompaction.instance(
+    "reconciles stale Next Steps with the preserved recent tail audit",
+    () => {
+      const stub = llm()
+      const stale = `## Goal
+- Fix compaction summaries
+
+## Progress
+### Done
+- Implemented the fix
+
+## Next Steps
+- run tests`
+      const reconciled = `## Goal
+- Fix compaction summaries
+
+## Progress
+### Done
+- Implemented the fix
+- tests were run and passed
+
+## Next Steps
+- (none)`
+      stub.push((input) =>
+        reply(JSON.stringify(input.messages.at(-1)).includes("tests were run and passed") ? reconciled : stale)(input),
+      )
+
+      return Effect.gen(function* () {
+        const test = yield* TestInstance
+        const ssn = yield* SessionNs.Service
+        const session = yield* ssn.create({})
+        yield* createUserMessage(session.id, "implement a compaction fix")
+        yield* createCompactionMarker(session.id)
+        const previousParent = (yield* ssn.messages({ sessionID: session.id })).at(-1)?.info.id
+        expect(previousParent).toBeTruthy()
+        yield* createSummaryAssistantMessage(session.id, previousParent!, test.directory, stale)
+
+        const runTests = yield* createUserMessage(session.id, "run tests")
+        const passed = yield* createAssistantMessage(session.id, runTests.id, test.directory)
+        yield* ssn.updatePart({
+          id: PartID.ascending(),
+          messageID: passed.id,
+          sessionID: session.id,
+          type: "text",
+          text: "tests were run and passed",
+        })
+        yield* createUserMessage(session.id, "prepare final response")
+        yield* createCompactionMarker(session.id)
+
+        const msgs = yield* ssn.messages({ sessionID: session.id })
+        const parent = msgs.at(-1)?.info.id
+        expect(parent).toBeTruthy()
+        yield* SessionCompaction.use.process({ parentID: parent!, messages: msgs, sessionID: session.id, auto: false })
+
+        const summary = (yield* ssn.messages({ sessionID: session.id })).find(
+          (item) => item.info.role === "assistant" && item.info.parentID === parent!,
+        )
+        const text =
+          summary?.parts
+            .filter((part): part is MessageV2.TextPart => part.type === "text")
+            .map((part) => part.text)
+            .join("\n") ?? ""
+        expect(text).toContain("## Next Steps")
+        expect(text.match(/## Next Steps\n([\s\S]*?)(?:\n## |$)/)?.[1]?.toLowerCase() ?? "").not.toContain(
+          "run tests",
+        )
+      }).pipe(withCompaction({ llm: stub.layer, config: cfg({ preserve_recent_tokens: 10_000 }) }))
+    },
+    { git: true },
+  )
+
   itCompaction.instance(
     "anchors repeated compactions with the previous summary",
     () => {