feat(tape): add explicit subagent tape lineage

docs/FLOWS.md

@@ -115,7 +115,9 @@ sequenceDiagram
 ```
 
 当前本地 agent tools 包括文件系统、命令执行、chat settings、subagent orchestration 等能力。
-Subagent 会话以 `sessionKind='subagent'` 存储，父会话通过 tape merge/discard 处理子会话结果。
+Subagent 会话以 `sessionKind='subagent'` 存储；父会话写入同时冻结 child Tape incarnation 与 head 的
+Tape link，并通过显式 linked Tape view 回查子会话内容，不复制 child entries。reset/rebuild 后的 child
+必须重新 link，不能用复用的 entry ID 冒充旧快照。
 MCP/Skill/ToolPresenter 继续拥有资源和执行策略；LoopEngine 只依赖窄 port，不 import presenter。
 
 ## 4. 会话恢复、分页和搜索

docs/architecture/agent-system-layered-runtime/migration-and-validation.md

@@ -117,7 +117,8 @@ Do not rename, merge or recreate these stores in this goal:
 
 - user/final/tool facts remain monotonic and idempotent by provenance;
 - edit/delete are replacement/retraction facts, not in-place Tape mutation;
-- effective view, bootstrap/backfill, anchors, handoff/fork/merge/discard remain compatible;
+- effective view, bootstrap/backfill, anchors, handoff, true-fork merge/discard, and production
+  subagent Tape links remain compatible;
 - one ViewManifest write is synchronously attempted before each actual provider request at the current point;
   write failure logs and remains fail-open, so a request may legally have no manifest;
 - trace/replay default remains metadata-only; raw payload inclusion stays opt-in;

docs/architecture/agent-system-layered-runtime/modules/shared-data-and-io.md

@@ -120,7 +120,8 @@ interface AgentSharedDataPorts {
 - `AgentTranscriptReadPort` 服务 title/history/export/message lookup；
 - `AgentTranscriptMutationPort` 服务 clear/edit/delete/fork/retry preparation，retry preparation 继续执行原
   summary 与 Memory invalidation，再把合法 input 交给当前 backend；
-- `AgentTapePort` 服务 query/handoff/replay 与 subagent merge/discard。
+- `AgentTapePort` 服务 query/handoff/replay、显式 linked Tape view 与 production subagent link
+  finalization。
 
 当前这些 port 由 `AgentRuntimePresenter` 作为过渡 adapter 实现，但 direct ACP 的网络 prompt、pending、
 permission、generation 和 ACP control 不通过该 presenter 执行。后续 ownership slice 可以替换 adapter，

docs/architecture/agent-system-layered-runtime/modules/tape-and-observability.md

@@ -16,6 +16,9 @@
 > ASLR-080 added a pure-read causal observation slice in the existing Tape service. It joins only persisted
 > facts and reports the renderer event-history gap explicitly. ASLR-081 proved the reader does not mutate Tape,
 > projections, replay state or Memory ingestion; the event-history gap remains explicit and unresolved.
+> Subagent Tape lineage now separates true fork merge from production subagent finalization. True fork deltas
+> and their receipt commit atomically; production children remain independent Tapes linked by a frozen-head
+> `subagent/tape_linked` event and exposed only through an explicit, authorized, read-only View scope.
 
 ## 1. 模块目的
 
@@ -107,6 +110,33 @@ error、记录 warning 并返回 `null`，保持请求 fail-open。
 - message projection 与 Tape 无法单事务时，保持当前 commit/recovery 顺序并测试 crash window；
 - Memory extraction 使用 effective Tape lineage，不从临时 mutable blocks 猜测最终事实。
 
+### True fork 与 production subagent lineage
+
+- true fork 在创建时记录精确 parent head，在 merge 开始时冻结 fork head；只复制 cutoff 内的 semantic
+  delta，排除 `session/start` 与 `fork/start`；
+- copied delta 与 parent `fork/merge` receipt 在同一 SQLite transaction 中 append；失败不留下部分 delta，
+  已提交 retry 复用并校验既有 receipt；
+- production subagent 是 durable child session/Tape，其 child entries 不进入 parent effective view。
+  结算统一调用 typed `linkSubagentTape()`，以 `completed | error | cancelled` outcome append
+  idempotent `subagent/tape_linked`；
+- link receipt 冻结 child head/count，link event 同时冻结 child Tape incarnation identity。缺失
+  capability 或 append 失败不得把任务标记为 Tape finalized；
+- legacy external `fork/merge` 可在 direct-child ownership 成立时作为 completed link 读取；legacy
+  `fork/discard` 只保留 audit 语义。true fork receipt 不会被误判为 external child link。
+
+### Cross-Tape recall
+
+- `AgentTapeViewScope` 只允许 `current | linked_subagents | current_and_linked`，默认仍是 `current`；
+- linked source 每次读取都以 `new_sessions` 的 persisted direct-child relationship 授权，并同时校验
+  link 的 Tape incarnation identity 与 frozen head；不递归 grandchildren，不接受任意 session id；
+- search result 携带 source `sessionId` 并在所有 source 合并后应用一个 global limit；context 的
+  `sourceSessionId` 每次只展开一个 Tape，窗口不跨 source；
+- linked read 不触发 bootstrap、backfill、projection/FTS repair、Memory ingestion 或 event publish；已
+  finalize 但被单独删除或 reset/rebuild 的 child 明确返回 unavailable，直到新 incarnation 被重新
+  link；
+- model surface 仍只有 `tape_search` 与 `tape_context`，没有第三个 tool，也不会把 linked child 自动注入
+  provider context。
+
 ## 7. ViewManifest 与 trace
 
 ViewManifest 记录 context 的构成、policy/version、source entry references、summary/reconstruction 等可审计

docs/architecture/deepchat-tape-baseline/spec.md

@@ -5,8 +5,9 @@ Status: current implementation baseline. Retained Tape implementation specs are
 [deepchat-tape-replay-contract](../deepchat-tape-replay-contract/spec.md),
 [deepchat-tape-view-assembler](../deepchat-tape-view-assembler/spec.md),
 [deepchat-tape-view-policy](../deepchat-tape-view-policy/spec.md),
-[deepchat-tape-policy-provenance](../deepchat-tape-policy-provenance/spec.md), and
-[deepchat-tape-policy-selector](../deepchat-tape-policy-selector/spec.md).
+[deepchat-tape-policy-provenance](../deepchat-tape-policy-provenance/spec.md),
+[deepchat-tape-policy-selector](../deepchat-tape-policy-selector/spec.md), and
+[subagent-tape-lineage](../subagent-tape-lineage/spec.md).
 
 This document keeps the Tape vision aligned with the current DeepChat codebase. The implementation
 path is:
@@ -37,7 +38,8 @@ DeepChat already has the main Tape primitives.
 | View policy | `tapeViewPolicy.ts` | Registry and selector boundary; `legacy_context_v1` delegates to the current selector. |
 | Context selection | `contextBuilder.ts` | Legacy token-budget selector used by `legacy_context_v1`. |
 | Request trace | `deepchat_message_traces` | Stores redacted provider request previews for the trace dialog. |
-| Model recall tools | `agentTapeTools.ts` | Exposes the atomic `tape_search` / `tape_context` pair only when both runtime ports are available for a persisted DeepChat session. |
+| Tape lineage | `DeepChatTapeService` + `new_sessions` | Keeps true forks as copy-on-merge branches and production subagents as independently readable, frozen-head Tape links. |
+| Model recall tools | `agentTapeTools.ts` | Exposes the atomic `tape_search` / `tape_context` pair only when both runtime ports are available for a persisted DeepChat session; linked-subagent recall is an explicit scope on the same pair. |
 | Diagnostic/runtime APIs | `DeepChatTapeService` + `SessionProjectionCoordinator` | Retains info, anchor listing, and handoff below the model-tool boundary; these capabilities are not user-configurable Agent tools. |
 
 The first implementation step uses this baseline as the single runtime path. `DeepChatTapeService`
@@ -60,11 +62,14 @@ docs/architecture/deepchat-tape-policy-provenance/
 └── spec.md
 docs/architecture/deepchat-tape-policy-selector/
 └── spec.md
+docs/architecture/subagent-tape-lineage/
+└── spec.md
 ```
 
 The retained scopes are `Existing TapeService + ViewManifest shadow mode`, replay/export
 contracts, `TapeViewAssembler` as the production context assembly entry, and `TapeViewPolicy` as
-the policy replacement boundary, `ViewManifest` policy provenance, and policy selector registry.
+the policy replacement boundary, `ViewManifest` policy provenance, policy selector registry, and
+the distinction between true fork merge and production subagent Tape links.
 
 ## Scope Boundary
 
@@ -86,7 +91,8 @@ the policy replacement boundary, `ViewManifest` policy provenance, and policy se
 ### Deferred scope for the first increment
 
 - Creating a separate TapeStore abstraction.
-- Memory graph retrieval, embedding-backed topic clustering, and cross-session recall.
+- Memory graph retrieval, embedding-backed topic clustering, and unrestricted or recursive
+  cross-session recall. Explicit recall of finalized direct-subagent Tape links is implemented.
 - Live LLM replay in CI.
 - Full eval pipeline and training exports.
 
@@ -99,6 +105,24 @@ the policy replacement boundary, `ViewManifest` policy provenance, and policy se
    manifest.
 5. Keep old sessions compatible through existing lazy backfill and bootstrap anchors.
 6. Treat `ViewManifest` as an explanation and regression artifact until parity is proven.
+7. Treat persisted session ownership as the authorization source for linked Tape reads. Link events
+   freeze readable child heads but never copy child entries into the parent effective view.
+
+## Subagent Tape Lineage
+
+Production subagents own durable, independent Tapes. Finalization appends one idempotent
+`subagent/tape_linked` event to the parent with a closed lifecycle outcome and frozen child head;
+missing capability or failed persistence leaves finalization retryable. The parent can explicitly
+search finalized direct children through `linked_subagents` or `current_and_linked`, and can expand
+context within one authorized source Tape by `sourceSessionId`. These reads are bounded by the link
+head and the linked child Tape incarnation; clearing and rebuilding a child cannot reuse entry IDs
+to impersonate the snapshot. Reads do not bootstrap, backfill, repair projections, or mutate Memory
+state.
+
+True forks retain different semantics: their selected delta and `fork/merge` receipt append to the
+parent in one SQLite transaction, retries reuse the committed receipt, and branch-local control
+anchors are excluded. Legacy external `fork/merge` records remain readable as child links;
+`fork/discard` remains audit-only. No database schema migration or third model tool was added.
 
 ## Target Flow
 

docs/architecture/retire-agent-session-presenter/spec.md

@@ -81,7 +81,7 @@ No object may re-export all four capability groups.
 | --- | --- |
 | create, detached create, subagent create, draft ensure, fork, delete | Lifecycle |
 | send, steer, pending input, message mutation, compaction, cancel, interaction | Turn |
-| transfer, runtime settings, ACP config/commands, subagent Tape merge/discard | AgentAssignment |
+| transfer, runtime settings, ACP config/commands, subagent Tape link | AgentAssignment |
 | session/message/Tape reads, window activation, rename/pin, title/status events | Projection |
 | permission cleanup | existing `SessionPermissionPort` |
 

docs/architecture/session-application-coordinators/spec.md

@@ -138,7 +138,7 @@ Owns executable assignment and runtime-setting policy:
 - transfer impact, batch move/delete, and single-session transfer;
 - model, project, permission, generation settings, disabled tools, and subagent-enabled settings;
 - ACP config options and commands;
-- subagent Tape merge/discard.
+- subagent Tape link finalization.
 
 Session deletion remains a lifecycle transaction. Assignment may call a required narrow lifecycle
 deletion port, but the composition graph must not use optional setters or circular construction.
@@ -253,8 +253,8 @@ defined as `Pick<IAgentSessionPresenter, ...>` and must not be grouped under a r
 - Project updates retain their current non-transactional order; no rollback is introduced.
 - ACP model lock, workdir requirement, permission modes, generation settings, disabled tools, and
   config/command behavior remain unchanged.
-- Subagent parent/slot/agent validation, ACP forced runtime settings, and Tape merge/discard parent
-  checks remain unchanged.
+- Subagent parent/slot/agent validation, ACP forced runtime settings, and Tape link parent-child
+  checks remain explicit at finalization.
 
 ### Projection
 

docs/architecture/session-management.md

@@ -110,7 +110,8 @@ ACP-provider source 只清 compatibility binding，不被误判成 direct ACP。
 ## Subagent、remote 与 cron
 
 - Subagent 与普通 session 共享 app/message schema，用 `sessionKind`、`parentSessionId`、`subagentMeta`
-  区分；child backend 仍由 manager 选择，父 session 通过 Tape merge/discard 接收结果。
+  区分；child backend 仍由 manager 选择。子任务结算时父 session 记录 frozen-head Tape link；显式
+  cross-Tape View 只读 direct child，child entries 不复制进父 effective view。
 - Remote 通过四个 consumer-owned session ports 调用 coordinator；active-generation lookup/cancel 仍使用
   `AgentManagerGenerationPort`，不扫描 presenter runtime maps。
 - Cron 的 composition-owned starter 通过 Lifecycle 创建 detached app session、通过 Turn send/cancel；

docs/architecture/subagent-run-guardrails/spec.md

@@ -1,6 +1,6 @@
 # Subagent Run Guardrails - Spec
 
-> Status: **implemented; final validation pending**
+> Status: **implemented and validated**
 
 ## Problem
 
@@ -29,9 +29,9 @@ inconsistent.
 - Foreground and background runs enforce the same deadline.
 - `list`, `info`, `log`, `wait`, and `kill` keep their existing meanings and run ownership checks.
 - Serialized run data includes the configured timeout, absolute deadline, and cancellation reason.
-- Manual cancellation, recursion prevention, and completed/error tape merge/discard behavior stay
-  compatible.
-- A cancelled child tape is not discarded until the child cancellation request settles; the run
+- Manual cancellation and recursion prevention stay compatible. Completed, errored, and cancelled
+  children are finalized through a frozen-head Tape link.
+- A cancelled child Tape is not linked until the child cancellation request settles; the run
   deadline itself still resolves without waiting for a blocked cancellation request.
 - Focused fake-timer, capacity, serialization, and handoff tests pass.
 

docs/architecture/subagent-tape-lineage/plan.md

@@ -0,0 +1,110 @@
+# Subagent Tape Lineage - Implementation Plan
+
+## Phase 1: Specify the boundary
+
+- Record the distinction between true fork merge and durable subagent link.
+- Freeze the event, outcome, authorization, head-cutoff, compatibility, and read-only view
+  contracts before changing production code.
+- Keep the current session relationship as the topology and authorization source of truth.
+
+## Phase 2: Harden true fork merge
+
+- Persist the exact parent head in `fork/start`.
+- Freeze the fork head when merge begins and select only entries at or below it.
+- Exclude `session/start` and `fork/start` from copied delta entries.
+- Add a narrow Tape-store transaction operation so copied delta and `fork/merge` receipt commit or
+  roll back together.
+- Use stable merge provenance to return an existing receipt on retry.
+- Reject missing, discarded, or malformed fork starts before creating a merge receipt, while
+  preserving retries of an already committed receipt after cleanup.
+- Cover valid empty forks, missing/discarded forks, injected append failure, retry, and concurrent
+  tail append boundaries with native SQLite tests.
+
+## Phase 3: Model production subagents as links
+
+- Add typed `SubagentTapeLinkInput`, `SubagentTapeLinkOutcome`, and `SubagentTapeLinkReceipt`
+  contracts at the shared runtime boundary.
+- Replace `mergeSubagentTape` and `discardSubagentTape` ports with one `linkSubagentTape` port across
+  DeepChat, direct ACP, session assignment, presenter, and tool runtime adapters.
+- Append `subagent/tape_linked` with stable task provenance, a frozen child head/count, and a
+  cryptographic identity of the child Tape incarnation.
+- Update orchestration finalization so completed, error, and cancelled tasks all link after child
+  settlement, while absent/failed capability leaves the task retryable. Polling retries a terminal
+  task even while sibling tasks remain active, without blocking on an in-flight link.
+- Reconcile terminal runtime status observed before handoff settlement as soon as the task enters
+  its started state.
+- Preserve legacy event reads without producing new legacy external fork records.
+
+## Phase 4: Add authorized linked Tape views
+
+- Introduce `AgentTapeViewScope` and a resolver that returns the current source and/or finalized
+  direct-child sources with immutable cutoffs.
+- Reuse persisted session ownership for authorization and Tape events for finalized snapshots.
+- Give newly created Tape bootstraps an opaque incarnation marker; derive a compatible stable
+  identity for existing unmarked Tapes without rewriting them.
+- Validate linked incarnation identities through one batched first-entry query so reset/rebuild
+  cannot reuse entry IDs to impersonate the frozen snapshot.
+- Resolve child ownership in one indexed JSON-set query so linked-source count cannot exhaust the
+  SQLite bind-variable limit.
+- Extend projection/FTS reads to query a bounded authorized source set, enforce per-source cutoffs,
+  and apply one global result limit.
+- Use projection/FTS ranking only for complete exact-head coverage; on partial freshness, fall back
+  all selected sources together so result scores remain comparable.
+- Add source `sessionId` to search results.
+- Extend context reads with `sourceSessionId`, reject mixed or unauthorized sources, and keep one
+  context window within one Tape.
+- Return explicit diagnostics for deleted or unavailable linked Tapes without triggering bootstrap,
+  backfill, or repair writes.
+- Build linked context evidence and summaries from the bounded authoritative rows already read at
+  the frozen head, without consulting a projection at a different freshness boundary.
+
+## Phase 5: Expose cross-Tape recall through existing tools
+
+- Add optional `scope` to `tape_search` and optional `sourceSessionId` to `tape_context`.
+- Keep omitted fields compatible with current-session-only recall.
+- Carry the types through tool manager, runtime session routes, DeepChat backend, and direct ACP
+  backend without adding another model tool.
+- Add tool-schema, route, ownership, ACP, global-limit, and parent-effective-view non-interference
+  tests.
+
+## Phase 6: Validate and finalize contracts
+
+- Review the complete branch diff against hidden writes, compatibility, transactionality, edge
+  cases, performance, authorization, naming, test depth, and future maintenance cost.
+- Run focused Tape/orchestrator/tool tests, native SQLite tests, main tests, typecheck, i18n, lint,
+  format, and format check.
+- Update the retained Tape baseline, runtime Tape contract, and this task ledger only for behavior
+  proven by the implementation and validation.
+- Do not run the full build in this slice because it refreshes unrelated provider and ACP registry
+  artifacts.
+
+## Commit Strategy
+
+1. `docs(tape): specify subagent tape lineage`
+2. `fix(tape): make fork merge atomic`
+3. `refactor(tape): model subagents as tape links`
+4. `feat(tape): add linked tape views`
+5. `feat(tools): add cross-tape recall`
+6. `docs(tape): finalize subagent tape lineage`
+
+If cumulative review finds an implementation defect not cleanly owned by the final documentation
+commit, add `fix(tape): address lineage review findings` without rewriting prior commits.
+
+## Review Gate
+
+Before every commit:
+
+1. Inspect status, full unstaged diff/stat/check, and run the smallest sufficient validation.
+2. Review P0 through P3 for hidden side effects, compatibility, boundaries, performance, security,
+   semantic naming, test gaps, and maintenance cost.
+3. Fix every in-scope actionable finding and repeat the review.
+4. Stage explicit task paths only; inspect full staged diff/check and repeat the same severity review.
+5. Commit only when staged changes contain no unrelated file and no actionable P0-P3 finding.
+
+## Rollback and Compatibility
+
+- The change adds no database schema migration; rollback leaves append-only link events readable as
+  inert unknown events by older code.
+- Current-only tool calls and true fork event readers remain compatible.
+- New code keeps a legacy reader for old external `fork/merge` events.
+- No child Tape is deleted or copied as part of production subagent finalization.