refactor(agent-core-v2): carry the context fold cursor in state and converge fold/projection internals

packages/agent-core-v2/AGENTS.md

@@ -86,7 +86,7 @@ One accepted exception: `features/tower/protocol` manages the `.tower/` director
 
 ## Conversation undo
 
-`context.undo` is the only persisted undo fact. `contextMemory/conversationTime.ts` owns the conversation clock (`isUndoAnchor` — the single tick predicate used by `computeUndoCut`, the checkpoint reducers, and the transcript reducer) and the checkpoint protocol. A wire Model whose state must follow conversation undo (todo, plan, task-notification delivery, …) **MUST** be defined with `defineCheckpointedModel` — never hand-roll the push/clear/restore reducers — which also registers it into `CHECKPOINTED_MODELS` for the undo pipeline's pre-cut depth check. World-time state (turn counters, task registries, revision counters) must stay outside checkpointed Models.
+`context.undo` is the only persisted undo fact. `contextMemory/conversationTime.ts` owns the conversation clock (`isUndoAnchor` — the single tick predicate — plus `computeUndoCut` / `computeUndoCutFrom`, the single anchor-walk decision: applied destructively by the `context.undo` Op and non-destructively by the transcript reducer, so a blocked undo reads identically on both sides) and the checkpoint protocol. A wire Model whose state must follow conversation undo (todo, plan, task-notification delivery, …) **MUST** be defined with `defineCheckpointedModel` — never hand-roll the push/clear/restore reducers — which also registers it into `CHECKPOINTED_MODELS` for the undo pipeline's pre-cut depth check. World-time state (turn counters, task registries, revision counters) must stay outside checkpointed Models.
 
 ## Model-facing reminders
 

packages/agent-core-v2/docs/wire-manifest.d.ts

@@ -344,7 +344,7 @@ interface LlmRequestPayload {
   messageCount: number;
   turnStep?: string;
   attempt?: string;
-  projection?: 'strict' | 'media-degraded' | 'media-stripped';
+  projection?: 'strict' | 'media-degraded' | 'media-stripped' | 'strict-media-degraded' | 'strict-media-stripped';
   droppedCount?: number;
 }
 

packages/agent-core-v2/src/agent/contextMemory/compactionHandoff.ts

@@ -1,14 +1,6 @@
 /**
- * `contextMemory` domain helper — derives the v1-compatible full-compaction
- * handoff shape for live rewrites, wire replay, and snapshot reducers.
- *
- * Token budgeting runs through an injectable {@link TokenEstimate}: the live
- * path (`AgentContextMemoryService.applyCompaction`) passes the estimator
- * from `IAgentTokenCountingService` (the raw heuristics — the
- * `[token_counting]` strategy never gates internal estimates); the pure
- * wire-replay / reducer paths keep the same heuristics — their estimate
- * fallback only fires when a record lacks `tokensAfter`, so the measured
- * chain is unaffected.
+ * Builds the bounded context window produced by compaction and exposes the
+ * shared user-message selection rules used by live execution and replay.
  */
 
 import { estimateTokens, estimateTokensForMessage, estimateTokensForMessages } from '#/kosong/contract/tokens';
@@ -24,7 +16,6 @@ export const COMPACTION_ELISION_VARIANT = 'compaction_elision';
 
 type MessageLike = ContextMessage;
 
-/** Injectable token-count estimates; see the file header for who passes what. */
 export interface TokenEstimate {
   readonly text: (text: string) => number;
   readonly message: (message: MessageLike) => number;
@@ -51,15 +42,7 @@ export interface ContextCompactionShapeInput {
   readonly compactedCount: number;
   readonly tokensBefore: number;
   readonly tokensAfter?: number;
-  /** Measured output tokens of the compaction LLM exchange — the REAL size of
-   *  the generated summary. Preferred over the summary-text estimate in the
-   *  `tokensAfter` fallback when present. */
   readonly summaryOutputTokens?: number;
-  /** Estimated fixed request overhead (system prompt + non-deferred tool
-   *  schemas) surviving the compaction; counted into the `tokensAfter`
-   *  fallback so the result stays on the same full-request basis as the
-   *  measured exchange anchors. Live path only — replay reads the persisted
-   *  `tokensAfter` verbatim. */
   readonly requestOverheadTokens?: number;
   readonly keptUserMessageCount?: number;
   readonly keptHeadUserMessageCount?: number;
@@ -139,6 +122,14 @@ export function buildContextCompactionShape(
   };
 }
 
+export function compactedWindowMessageCount(
+  keptUserMessageCount: number | undefined,
+  keptHeadUserMessageCount: number | undefined,
+): number | undefined {
+  if (keptUserMessageCount === undefined) return undefined;
+  return keptUserMessageCount + (keptHeadUserMessageCount === undefined ? 1 : 2);
+}
+
 export function buildCompactionSummaryText(summary: string): string {
   const suffix = summary.trim();
   return `${COMPACTION_SUMMARY_PREFIX}\n${suffix.length > 0 ? suffix : '(no summary available)'}`;

packages/agent-core-v2/src/agent/contextMemory/contextMemory.ts

@@ -1,6 +1,11 @@
+/**
+ * Declares the Agent-scoped context-memory contract and compaction handoff
+ * data shared by request, token-counting, and persistence consumers.
+ */
+
 import { createDecorator } from "#/_base/di/instantiation";
 
-import type { UndoCut } from './contextOps';
+import type { UndoCut } from './conversationTime';
 import type { LoopRecordedEvent } from './loopEventFold';
 import type { ContextMessage } from './types';
 
@@ -10,14 +15,7 @@ export interface ContextCompactionInput {
   readonly compactedCount: number;
   readonly tokensBefore: number;
   readonly tokensAfter?: number;
-  /** Measured output tokens of the compaction LLM exchange (the REAL summary
-   *  size); preferred over the summary-text estimate in the `tokensAfter`
-   *  fallback when present. */
   readonly summaryOutputTokens?: number;
-  /** Estimated fixed request overhead (system prompt + non-deferred tool
-   *  schemas) that every post-compaction exchange still carries. Counted into
-   *  the `tokensAfter` fallback so the result stays on the same full-request
-   *  basis as the measured exchange anchors. */
   readonly requestOverheadTokens?: number;
   readonly keptUserMessageCount?: number;
   readonly keptHeadUserMessageCount?: number;
@@ -40,6 +38,8 @@ export interface IAgentContextMemoryService {
 
   get(): readonly ContextMessage[];
 
+  getMessageLog(): readonly ContextMessage[];
+
   append(...messages: readonly ContextMessage[]): void;
 
   appendLoopEvent(event: LoopRecordedEvent): void;

packages/agent-core-v2/src/agent/contextMemory/contextMemoryService.ts

@@ -1,13 +1,6 @@
 /**
- * `contextMemory` domain — `IAgentContextMemoryService` implementation.
- *
- * Owns per-agent conversation history through `wire`, maintains measurements
- * with `tokenCounting`, and broadcasts live mutations through `event`. Every
- * splice-shaped mutation (`clear` / `applyCompaction` / `undo`, plus verified
- * cross-model trailing removal) publishes `context.spliced` from the live path
- * only — replay rebuilds silently — and truncates the measured-anchor ledger
- * when a cut crosses an anchor, letting `tokenCounting` restore the surviving
- * prefix's REAL size from the remaining anchors. Bound at Agent scope.
+ * Owns the Agent-scoped bounded context window, persists its mutations, keeps
+ * token anchors aligned, and publishes live splice events to consumers.
  */
 
 import { Disposable } from '#/_base/di/lifecycle';
@@ -30,16 +23,18 @@ import {
 } from './contextMemory';
 import { buildContextCompactionShape, type TokenEstimate } from './compactionHandoff';
 import {
-  computeUndoCut,
   ContextModel,
   contextAppendLoopEvent,
   contextAppendMessage,
   contextApplyCompaction,
   contextClear,
   contextUndo,
+} from './contextOps';
+import {
+  computeUndoCut,
   isFullyUndoable,
   type UndoCut,
-} from './contextOps';
+} from './conversationTime';
 import type { LoopRecordedEvent } from './loopEventFold';
 import type { ContextMessage } from './types';
 
@@ -54,7 +49,6 @@ declare module '#/app/event/eventBus' {
   }
 }
 
-// NOTE: stays Disposable — its own 'get' collides with the Fiber
 export class AgentContextMemoryService extends Disposable implements IAgentContextMemoryService {
   declare readonly _serviceBrand: undefined;
 
@@ -75,7 +69,11 @@ export class AgentContextMemoryService extends Disposable implements IAgentConte
   }
 
   get(): readonly ContextMessage[] {
-    return this.wire.getModel(ContextModel) as readonly ContextMessage[];
+    return this.getMessageLog();
+  }
+
+  getMessageLog(): readonly ContextMessage[] {
+    return this.wire.getModel(ContextModel).messages as readonly ContextMessage[];
   }
 
   append(...messages: readonly ContextMessage[]): void {
@@ -172,9 +170,6 @@ export class AgentContextMemoryService extends Disposable implements IAgentConte
   private sizeOpsForCut(cutIndex: number): Op[] {
     const model = this.wire.getModel(TokenCountingModel);
     if (!model.anchors.some((anchor) => anchor.length > cutIndex)) return [];
-    // The display tokens are the post-cut size computed from the CURRENT
-    // ledger — anchors at or below the cut are identical before and after
-    // the truncation, so the pre-dispatch read is exact.
     return [
       tokenCountingTruncated({
         length: cutIndex,