feat(channels): add rolling summaries and fork snapshots

docs/design/channel-conversation-continuity-v2-implementation-plan.md

@@ -1,6 +1,6 @@
 # Channel Conversation Continuity v2 Implementation Plan
 
-Status: G0 complete; S-1 and S0 merged; S1+S2, S3, and S4 implemented and locally verified; S5-S7 pending
+Status: G0 complete; S-1 and S0 merged; S1+S2, S3, S4, and S5 implemented and locally verified; S6-S7 pending
 Owner: conversation, channel context, Ling Agent Session, and storage maintainers
 Date: 2026-08-08
 Last verified: 2026-08-10
@@ -400,7 +400,7 @@ input accepted
 
 ## Slice S3: Context Segmentation And Shared Projection
 
-Status: implemented on `codex/continuity-v2-context-projector` and locally verified.
+Status: implemented on `codex/continuity-v2-context-projection` and locally verified.
 Contracts (`35/35`), Core (`355/355`), Daemon (`888/888`), Remote Protocol
 (`40/40`), and Web (`42/42`) tests pass; Web typecheck and `git diff --check` pass.
 Model-facing Channel consumers use the shared projector, including causally later queued
@@ -447,7 +447,7 @@ context. Paging for UI remains allowed; context construction goes through the pr
 
 ## Slice S4: Intent v2 And Issue #421 Closure
 
-Status: implemented on `codex/continuity-v2-context-projector`. The clean-break SQLite
+Status: implemented on `codex/continuity-v2-intent-v2`. The clean-break SQLite
 migration, contracts, API/client filters, selector, structured clarification, typed
 execution, Web diagnostics, and Issue #421 regression fixtures are locally verified.
 The focused channel workspace suite passes 186/186, including article continuation,
@@ -500,6 +500,11 @@ bad clarification -> unrelated snake game
 
 ## Slice S5: Proactive Summaries And Fork Snapshots
 
+Status: implemented on `codex/continuity-v2-summaries-snapshots` and locally verified.
+Core (`357/357`) and Daemon (`894/894`) tests pass, including provider-aware hard
+summarization, stable raw-tail reconstruction, stale-result fencing, immutable fork
+snapshot reconstruction, and the one strict context-length fallback.
+
 ### Changes
 
 - Add a summary coordinator that watches committed stable ranges per segment.
@@ -804,7 +809,7 @@ interfaces at the end of S3 and keep implementation files separate before parall
   - Verify: projection consistency, permission, correction, and consumer adapter tests.
 - [x] **T5 (P1, human: ~2 days / Codex: ~3-4 hours)**: cut intent decisions to v2 and satisfy issue #421 closure criteria.
   - Verify: daemon regression suite, explicit file safety, clarification actionability, and eval cases.
-- [ ] **T6 (P2, human: ~2 days / Codex: ~3-5 hours)**: add proactive summaries, coverage watermarks, stale-result rejection, and fork snapshots.
+- [x] **T6 (P2, human: ~2 days / Codex: ~3-5 hours)**: add proactive summaries, coverage watermarks, stale-result rejection, and fork snapshots.
   - Verify: budget, race, invalidation, reconstruction, and fallback tests.
 - [ ] **T7 (P2, human: ~2 days / Codex: ~3-5 hours)**: enforce multi-agent projection versions and private-memory isolation.
   - Verify: shared-core, stale fan-in, handoff, and security fixtures.

packages/core/src/conversation-context-store-types.ts

@@ -1,8 +1,11 @@
 import type {
   ContextSegment,
   ContextSegmentState,
+  ConversationContextSnapshot,
   ConversationContextSummary,
+  ConversationContextSummaryScope,
   ConversationDomainRef,
+  ConversationItemVisibilityV1,
   TurnContextAssignment,
   TurnContextAssignmentStatus,
   TurnContextDecisionSource,
@@ -51,3 +54,71 @@ export interface ListConversationContextSummariesOptions {
   readonly throughSequence?: number;
   readonly limit?: number;
 }
+
+export interface ConversationContextSummarySourceFence {
+  readonly itemId: string;
+  readonly sequence: number;
+  readonly revision: number;
+  readonly updatedAt: string;
+  readonly visibility: ConversationItemVisibilityV1;
+  readonly visibilityOwnerId?: string;
+  readonly turnId: string;
+  readonly assignmentId: string;
+  readonly assignmentRevision: number;
+}
+
+export interface CommitConversationContextSummaryInput {
+  readonly threadId: string;
+  readonly segmentId?: string;
+  readonly scope: ConversationContextSummaryScope;
+  readonly coveredFromSequence: number;
+  readonly coveredThroughSequence: number;
+  readonly objective?: string;
+  readonly decisions?: readonly string[];
+  readonly constraints?: readonly string[];
+  readonly openQuestions?: readonly string[];
+  readonly activeWorkRefs?: readonly ConversationDomainRef[];
+  readonly sourceRefs: readonly ConversationDomainRef[];
+  readonly policyVersion: string;
+  readonly projectionVersion: string;
+  readonly visibilityFingerprint: string;
+  readonly expectedActiveSummaryId: string | null;
+  readonly sourceFence: readonly ConversationContextSummarySourceFence[];
+}
+
+export type ConversationContextSummaryDiscardReason =
+  | "active_summary_changed"
+  | "segment_changed"
+  | "source_items_changed"
+  | "assignments_changed"
+  | "visibility_changed";
+
+export type CommitConversationContextSummaryResult =
+  | {
+      readonly status: "committed";
+      readonly summary: ConversationContextSummary;
+    }
+  | {
+      readonly status: "discarded_stale";
+      readonly reason: ConversationContextSummaryDiscardReason;
+    };
+
+export interface CreateConversationContextSnapshotInput {
+  readonly id?: string;
+  readonly threadId: string;
+  readonly segmentId: string;
+  readonly projectionVersion: string;
+  readonly throughItemSequence: number;
+  readonly summaryIds?: readonly string[];
+  readonly sourceRefs: readonly ConversationDomainRef[];
+  readonly policyVersion: string;
+}
+
+export interface ListConversationContextSnapshotsOptions {
+  readonly threadId: string;
+  readonly limit?: number;
+}
+
+export interface CreateConversationContextSnapshotResult {
+  readonly snapshot: ConversationContextSnapshot;
+}

packages/core/src/conversation-item-store-types.ts

@@ -68,6 +68,7 @@ export interface ListConversationItemsForSegmentOptions {
   readonly segmentId: string;
   readonly throughSequence: number;
   readonly afterSequence?: number;
+  readonly order?: "oldest" | "newest";
   readonly limit?: number;
 }
 

packages/core/src/conversation-thread-topology-types.ts

@@ -1,4 +1,5 @@
 import type { LingThread } from "./run-types.js";
+import type { CreateConversationContextSnapshotInput } from "./conversation-context-store-types.js";
 
 interface ConversationThreadTopologyBaseInput {
   readonly id?: string;
@@ -19,6 +20,8 @@ export type ResolveOrCreateConversationThreadInput =
       readonly surfaceKind: "branch";
       readonly parentThreadId: string;
       readonly parentTurnId: string;
+      readonly forkedFromRunId?: string;
+      readonly forkContextSnapshot: Omit<CreateConversationContextSnapshotInput, "threadId">;
     });
 
 export interface ResolveOrCreateConversationThreadResult {

packages/core/src/run-types.ts

@@ -1721,6 +1721,20 @@ export interface RunStore {
   listConversationContextSummaries(
     options: import("./conversation-context-store-types.js").ListConversationContextSummariesOptions,
   ): readonly import("@ling-stack/contracts").ConversationContextSummary[];
+  commitConversationContextSummary(
+    input: import("./conversation-context-store-types.js").CommitConversationContextSummaryInput,
+    now: string,
+  ): import("./conversation-context-store-types.js").CommitConversationContextSummaryResult;
+  createConversationContextSnapshot(
+    input: import("./conversation-context-store-types.js").CreateConversationContextSnapshotInput,
+    now: string,
+  ): import("@ling-stack/contracts").ConversationContextSnapshot;
+  getConversationContextSnapshot(
+    id: string,
+  ): import("@ling-stack/contracts").ConversationContextSnapshot | undefined;
+  listConversationContextSnapshots(
+    options: import("./conversation-context-store-types.js").ListConversationContextSnapshotsOptions,
+  ): readonly import("@ling-stack/contracts").ConversationContextSnapshot[];
   createChannelMessageRouteDecision(input: CreateChannelMessageRouteDecisionInput, now: string): ChannelMessageRouteDecision;
   getChannelMessageRouteDecision(id: string): ChannelMessageRouteDecision | undefined;
   listChannelMessageRouteDecisions(options?: ListChannelMessageRouteDecisionsOptions): ChannelMessageRouteDecision[];
@@ -2278,6 +2292,10 @@ export type ChannelStoreFacet = RunStoreFacet<
   | "applyTurnContextAssignment"
   | "getConversationContextSummary"
   | "listConversationContextSummaries"
+  | "commitConversationContextSummary"
+  | "createConversationContextSnapshot"
+  | "getConversationContextSnapshot"
+  | "listConversationContextSnapshots"
   | "createChannelMessageRouteDecision"
   | "getChannelMessageRouteDecision"
   | "listChannelMessageRouteDecisions"

packages/core/src/storage/sqlite-run-store.ts

@@ -746,6 +746,8 @@ export class SqliteRunStore implements RunStore {
       {
         createLingThread: (input, now) => this.lingThreads.createLingThread(input, now),
         getLingThread: (threadId) => this.lingThreads.getLingThread(threadId),
+        createConversationContextSnapshotWithinTransaction: (input, now) =>
+          this.conversationContext.createConversationContextSnapshotWithinTransaction(input, now),
       },
     );
     this.lingThreadCleanup = new SqliteLingThreadCleanupStore(
@@ -2547,6 +2549,32 @@ export class SqliteRunStore implements RunStore {
     return this.conversationContext.listConversationContextSummaries(options);
   }
 
+  commitConversationContextSummary(
+    input: import("../conversation-context-store-types.js").CommitConversationContextSummaryInput,
+    now: string,
+  ): import("../conversation-context-store-types.js").CommitConversationContextSummaryResult {
+    return this.conversationContext.commitConversationContextSummary(input, now);
+  }
+
+  createConversationContextSnapshot(
+    input: import("../conversation-context-store-types.js").CreateConversationContextSnapshotInput,
+    now: string,
+  ): import("@ling-stack/contracts").ConversationContextSnapshot {
+    return this.conversationContext.createConversationContextSnapshot(input, now);
+  }
+
+  getConversationContextSnapshot(
+    id: string,
+  ): import("@ling-stack/contracts").ConversationContextSnapshot | undefined {
+    return this.conversationContext.getConversationContextSnapshot(id);
+  }
+
+  listConversationContextSnapshots(
+    options: import("../conversation-context-store-types.js").ListConversationContextSnapshotsOptions,
+  ): readonly import("@ling-stack/contracts").ConversationContextSnapshot[] {
+    return this.conversationContext.listConversationContextSnapshots(options);
+  }
+
   createChannelMessage(input: CreateChannelMessageInput, now: string): ChannelMessage {
     if (this.legacyContinuityFixtureMode) return this.createLegacyChannelMessageFixture(input, now);
     const channel = this.getChannel(input.channelId);