refactor(core): move the replay divergence implementation into src/core

replay-divergence.ts mixed the wire vocabulary every zone reads with the
sanitizing, bounding and reporting implementation only root zones call. The
ten value consumers are all root (daemon replay, the session replay
coordinator, the daemon client lifecycle, the replay-test reporter, the
command error projection, and the MCP tool error), so the implementation moves
to src/core/replay-divergence.ts and carries its test unchanged.

The types stay in contracts and keep the @agent-device/contracts/divergence
subpath, which packages/ad-replay and packages/selectors type-import.
ReplayVarScrubEntry follows the implementation: it is the sanitizer's own
parameter shape, not part of the divergence wire report.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SdXHhx9NkfH1PT4XjYe7tE

Author: claude

packages/contracts/src/facades/divergence.ts

@@ -1,18 +1,3 @@
-export {
-  REPLAY_DIVERGENCE_DEFAULT_REF_LIMIT,
-  REPLAY_DIVERGENCE_DIGEST_REF_LIMIT,
-  REPLAY_DIVERGENCE_LEVEL_BYTE_LIMITS,
-  REPLAY_DIVERGENCE_SUGGESTION_LIMIT,
-  applyReplayDivergenceLevelCaps,
-  boundReplayDivergence,
-  createReplayDivergenceSanitizer,
-  formatReplayDivergenceReport,
-  measureReplayDivergenceBytes,
-  readReplayDivergenceResume,
-  sanitizeReplayDivergenceField,
-  scrubReplayVarValues,
-  truncateUtf8Field,
-} from '../replay-divergence.ts';
 export type {
   ReplayDivergence,
   ReplayDivergenceCause,
@@ -30,5 +15,4 @@ export type {
   ReplayDivergenceTargetCandidate,
   ReplayDivergenceTargetIdentity,
   ReplayRepairHint,
-  ReplayVarScrubEntry,
 } from '../replay-divergence.ts';

packages/contracts/src/replay-divergence.ts

@@ -6,7 +6,7 @@ import {
 } from '../progress.ts';
 import { formatDurationSeconds } from '../duration-format.ts';
 import { colorize, supportsColor } from '../../../commands/output/color.ts';
-import { formatReplayDivergenceReport } from '@agent-device/contracts/divergence';
+import { formatReplayDivergenceReport } from '../../../core/replay-divergence.ts';
 import type {
   ReplayTestReporter,
   ReplayTestReporterContext,

src/cli/replay-test/reporters/default.ts

@@ -5,7 +5,7 @@ import {
   type ErrorCandidateView,
   type NormalizedError,
 } from '@agent-device/kernel/errors';
-import { formatReplayDivergenceReport } from '@agent-device/contracts/divergence';
+import { formatReplayDivergenceReport } from '../../core/replay-divergence.ts';
 
 export function printHumanError(
   err: AppError | NormalizedError,

src/commands/output/error.ts

@@ -11,8 +11,8 @@ import {
   REPLAY_DIVERGENCE_LEVEL_BYTE_LIMITS,
   REPLAY_DIVERGENCE_SUGGESTION_LIMIT,
   truncateUtf8Field,
-  type ReplayDivergence,
 } from './replay-divergence.ts';
+import type { ReplayDivergence } from '@agent-device/contracts/divergence';
 
 function buildDivergence(overrides: Partial<ReplayDivergence> = {}): ReplayDivergence {
   return {

…/contracts/src/replay-divergence.test.ts src/core/replay-divergence.test.tspackages/contracts/src/replay-divergence.test.ts renamed to src/core/replay-divergence.test.ts packages/contracts/src/replay-divergence.test.ts renamed to src/core/replay-divergence.test.ts

@@ -3,7 +3,7 @@ import net from 'node:net';
 import os from 'node:os';
 import path from 'node:path';
 import { AppError, normalizeError } from '@agent-device/kernel/errors';
-import { readReplayDivergenceResume } from '@agent-device/contracts/divergence';
+import { readReplayDivergenceResume } from '../../core/replay-divergence.ts';
 import type { DaemonRequest, DaemonResponse } from '../daemon-request.ts';
 import {
   runCmdDetachedMonitored,

src/core/replay-divergence.ts

@@ -14,7 +14,7 @@ import { runReplayForTest } from '../../__tests__/replay-command-fixture.ts';
 import { SessionStore } from '../../../session-store.ts';
 import type { DaemonResponse } from '../../../daemon-request.ts';
 import { makeIosSession } from '../../../../__tests__/test-utils/session-factories.ts';
-import { formatReplayDivergenceReport } from '@agent-device/contracts/divergence';
+import { formatReplayDivergenceReport } from '../../../../core/replay-divergence.ts';
 import { maestroScriptSourceBundleFor } from '../../../../__tests__/test-utils/replay-script-source.ts';
 import {
   captureSnapshotThroughLegacyDispatchFixture,

src/daemon/client/daemon-client-lifecycle.ts

@@ -2,7 +2,8 @@ import fs from 'node:fs';
 import path from 'node:path';
 import type { ResponseLevel } from '@agent-device/kernel/contracts';
 import { redactDiagnosticData } from '@agent-device/kernel/redaction';
-import { boundReplayDivergence, type ReplayDivergence } from '@agent-device/contracts/divergence';
+import { type ReplayDivergence } from '@agent-device/contracts/divergence';
+import { boundReplayDivergence } from '../../../core/replay-divergence.ts';
 import {
   bindInternalObservationAuthority,
   type InternalObservationEvidence,

src/daemon/replay/internal/__tests__/session-replay-runtime-failure.test.ts

@@ -28,15 +28,17 @@ import type { ReplayReportAction } from './session-replay-report-action.ts';
 import { rankAndDedupeReplaySuggestions } from './session-replay-suggestion-ranking.ts';
 import type { SessionState } from '../../session-state.ts';
 import {
-  REPLAY_DIVERGENCE_SUGGESTION_LIMIT,
-  createReplayDivergenceSanitizer,
   type ReplayDivergence,
   type ReplayDivergenceScreen,
   type ReplayDivergenceScreenRef,
   type ReplayDivergenceSuggestion,
   type ReplayDivergenceSuggestionBasis,
-  type ReplayVarScrubEntry,
 } from '@agent-device/contracts/divergence';
+import {
+  REPLAY_DIVERGENCE_SUGGESTION_LIMIT,
+  createReplayDivergenceSanitizer,
+  type ReplayVarScrubEntry,
+} from '../../../core/replay-divergence.ts';
 
 export type DivergenceFieldSanitizer = (value: string, limit?: number) => string;