diff --git a/docs/architecture/llm-compaction-events-log-projection-draft.md b/docs/architecture/llm-compaction-events-log-projection-draft.md
index 9070ed180b..20ce170beb 100644
--- a/docs/architecture/llm-compaction-events-log-projection-draft.md
+++ b/docs/architecture/llm-compaction-events-log-projection-draft.md
@@ -7,7 +7,7 @@ counterpart: ./llm-compaction-events-log-projection-draft.zh-CN.md
 implementation_status: current
 document_status: draft
 translation_status: synced
-last_verified: 2026-08-14
+last_verified: 2026-08-28
 owners:
   - maka-backend
 ---
@@ -38,7 +38,7 @@ This chapter builds on Chapter 1's log-first Runtime and Chapter 2's distinction
 
 The primary subject is **RuntimeEvent history compaction**: a compactor produces either a continuation summary or provider-native compact state, the checkpoint covers a safe prefix of RuntimeEvents, and later requests use that projection in place of the prefix. The same planner and checkpoint transaction serve manual, pre-turn, mid-turn, and overflow triggers. The chapter does not fully cover active or stale pruning of individual Tool Results; those reduce provider messages without creating another LLM compaction mechanism.
 
-This chapter describes the implementation current as of 2026-08-23. Ledger-backed checkpoints use schema V2 for text summaries and schema V3 for provider-native state. OpenAI Codex subscription models use Codex remote compaction V2 by default; other providers retain text-summary behavior.
+This chapter describes the implementation current as of 2026-08-28. Ledger-backed checkpoints use schema V2 for text summaries and schema V3 for provider-native state. OpenAI Codex subscription models use Codex remote compaction V2 by default; other providers retain text-summary behavior.
 
 ## Start with a long-running Session
 
@@ -162,18 +162,21 @@ The prior-history path for a normal Send begins in `AiSdkBackend.buildPriorMessa
 1. Exclude the current `turnId` to obtain the prior Runtime context.
 2. Prepare the context-budget policy.
 3. Load the latest compatible ledger-backed checkpoint.
-4. Handle stale oversized Tool Results first.
-5. Calculate the history-compaction high water and retained tail.
-6. Validate whether an existing checkpoint exactly matches the source prefix.
-7. If the old checkpoint does not cover the new fold, call an LLM to create a rolling successor.
-8. Project a V2 checkpoint as a synthetic text RuntimeEvent, or carry a V3 checkpoint as explicit projection metadata, then append the uncovered raw tail.
-9. Build the provider replay plan and only then materialize `ModelMessage[]`.
+4. Validate and replay the existing checkpoint against the immutable RuntimeEvent sequence.
+5. Apply stale oversized Tool Result pruning only to the uncovered projected remainder.
+6. If the projected history still exceeds the budget, select a safe prefix and retained tail.
+7. If the old checkpoint does not cover the new fold, call a compactor to create a rolling successor.
+8. Validate and durably record the successor before using it.
+9. Project a V2 checkpoint as a synthetic text RuntimeEvent, or carry a V3 checkpoint as explicit projection metadata, then append the uncovered raw tail.
+10. Build the provider replay plan and only then materialize `ModelMessage[]`.
 
-The ordering reveals two properties.
+The ordering reveals three properties.
 
-First, compaction happens inside **model-history projection**, not inside the RuntimeEvent append path. Events already produced by the model and tools do not change when a later context budget changes.
+First, checkpoint source matching always sees the immutable RuntimeEvent ledger. Stale Tool Result pruning shapes only the uncovered replay remainder, so a moving recent-turn window cannot invalidate an otherwise matching checkpoint by changing the bytes used for its digest.
 
-Second, the checkpoint is not itself a canonical RuntimeEvent. Coverage and tail selection return the selected checkpoint explicitly alongside the projected RuntimeEvents. A V2 checkpoint also materializes as the familiar system-authored text block so ordinary replay planning can consume it. A compatible V3 checkpoint creates no synthetic text: the provider materializer prepends its assistant `openai.compaction` custom part directly. Neither representation is written back to the RuntimeEvent ledger as though it were an original interaction fact.
+Second, compaction happens inside **model-history projection**, not inside the RuntimeEvent append path. Events already produced by the model and tools do not change when a later context budget changes.
+
+Third, the checkpoint is not itself a canonical RuntimeEvent. Coverage and tail selection return the selected checkpoint explicitly alongside the projected RuntimeEvents. A V2 checkpoint also materializes as the familiar system-authored text block so ordinary replay planning can consume it. A compatible V3 checkpoint creates no synthetic text: the provider materializer prepends its assistant `openai.compaction` custom part directly. Neither representation is written back to the RuntimeEvent ledger as though it were an original interaction fact.
 
 ## Triggering ends before compaction begins
 
@@ -206,7 +209,11 @@ The LLM compactor produces a structured summary that another LLM can use to cont
 - Next Steps;
 - Critical Context, including exact paths, function names, commands, results, and errors.
 
-The summarizer sees newly folded user/model text and Tool Calls/Results. Thinking is intentionally omitted. Desktop reuses the Session's current connection and model and caps summary generation output at 4,096 tokens. The checkpoint builder then applies the current compact policy again to bound the final model-visible summary.
+The summarizer sees newly folded user/model text and Tool Calls/Results. Thinking is intentionally omitted. Runtime Host reuses the Session's selected connection, model, and provider options without imposing a compaction-only output-token cap. An output-length finish is rejected rather than admitted as a partial summary. The checkpoint builder preserves the complete accepted summary; the replay gate evaluates its full model-visible size instead of truncating it after generation.
+
+The text prompt and validator share one section template. A new V2 summary must contain substantive `Goal`, `Progress`, `Next Steps`, and `Critical Context` sections in order, must not end inside an open fence or other truncation marker, and must not be disproportionately small: a fold above 10,000 estimated tokens requires at least 200 estimated summary tokens. A malformed first completion gets exactly one stricter repair request, and the checkpoint write gate validates the result again.
+
+Malformed retries are bounded beyond that repair. Runtime remembers up to 16 exact malformed-input fingerprints per Session backend, covering the connection, model, route, policy and input budgets, request shape, previous checkpoint, and folded source events. The same unchanged input fails open without another provider dispatch; changed source or configuration is eligible again. Cancellation does not arm this circuit. Granular `malformed_summary_*` reasons survive into compaction diagnostics and terminal context-budget detail.
 
 The LLM does not decide:
 
@@ -309,16 +316,18 @@ Two related logs must remain distinct:
 
 In other words, **the projection is also persisted as an event**. This is not circular. The checkpoint event is not one of the source events it covers. It records the fact that the system accepted this projection during a particular Run. The original RuntimeEvents remain independently durable.
 
-AgentRunStore also maintains a bounded event projection for fast checkpoint lookup. Its write order is intentional:
+AgentRunStore also maintains a bounded event projection for fast checkpoint lookup. The canonical event and its derived projection are written in one SQLite transaction:
 
 ```text
-append canonical AgentRunEvent
-  → then update bounded checkpoint projection
+BEGIN write transaction
+  → insert canonical AgentRunEvent
+  → update bounded checkpoint projection
+COMMIT both
 ```
 
-If canonical append fails, the projection must not remain. If projection update fails, the canonical event is already durable and cold-start recovery can rebuild the projection from Run ledgers.
+The SQL statement order remains log first, but there is no partial durability boundary between the two writes: if either statement fails, the transaction rolls back both. The AgentRunEvent ledger remains authoritative because an uninitialized, legacy, or damaged projection can still be rebuilt from it, not because current writes intentionally allow the event and projection to commit separately.
 
-This is the familiar log-first rule: an index may be missing; it may not pretend that a fact was committed.
+This is the familiar log-first rule under an atomic commit: the derived row may be rebuilt, and it may never describe a fact absent from the canonical ledger.
 
 ## Cold-start recovery: rebuild a damaged projection from the log
 
@@ -348,13 +357,12 @@ This diagram explains checkpoint-lookup recovery; it does not imply that the Run
 
 ## Replay: current policy judges the checkpoint again
 
-A checkpoint that was once valid is not guaranteed to fit every future request. The model may change, its context window may shrink, or an operator may tighten `maxBlockEstimatedTokens` or `maxEstimatedTokens`.
+A checkpoint that was once valid is not guaranteed to fit every future request. The selected model may change, its context window may shrink, or Runtime may derive a smaller `maxHistoryEstimatedTokens` from current model facts.
 
-`evaluateHistoryCompactCheckpointReplay()` is the single policy gate through which a checkpoint enters model history. It recomputes the model-visible token estimate and checks that:
+`evaluateHistoryCompactCheckpointReplay()` is the single current-policy fit gate through which a source-matched checkpoint enters model history. It recomputes the V2 model-visible checkpoint estimate (or uses the V3 estimate) and checks that:
 
-- the checkpoint is within the per-block limit;
-- it is within the total compact-projection limit;
-- checkpoint plus replay tail is within the current history budget.
+- checkpoint plus replay tail is within the current history budget;
+- when the source projection is available for comparison, the replacement is strictly smaller than that source.
 
 A projection may replay only when both source matching and current-policy fit succeed.
 
@@ -383,7 +391,8 @@ Compaction crosses token estimation, an LLM call, schema construction, durable a
 | Failure point | Current behavior | What must not happen |
 |---|---|---|
 | Below high water | Keep the existing projection or apply ordinary budget selection | Create an unsourced summary as a speculative optimization |
-| LLM returns an empty summary | Record no new checkpoint; on the first compact, retain only a safe raw tail | Treat an empty projection as covered history |
+| LLM returns an empty summary | Record no new checkpoint. Automatic pre-turn compaction keeps the original source-derived projection and, if it remains over budget, terminates with `context_budget_exhausted` without writing a failure note; manual compaction records one visible `context_compaction_failed_open` note | Treat an empty projection as covered history |
+| Text summary is malformed | Spend one stricter repair attempt, then fail open with a granular reason; do not redispatch an unchanged failed fingerprint | Persist incomplete structure or loop on the same doomed compaction input |
 | Codex returns no unique valid compact item | Record no new checkpoint and use the same fail-open path | Persist partial or ambiguous provider state |
 | Compaction input cannot fit after bounded Tool Result omission | Do not dispatch the compaction request; use the same fail-open path | Ask the provider to compact an already over-capacity request |
 | Rolling summarizer fails | Reuse the old checkpoint if it still matches and fits, then add the newest complete raw Turns that fit | Pretend the old checkpoint covers newly evicted events |
@@ -393,7 +402,7 @@ Compaction crosses token estimation, an LLM call, schema construction, durable a
 | Bounded projection is damaged | Recover from canonical AgentRun ledgers and repair the projection | Treat the cache as the only source of truth |
 | User stops manual compaction | Abort the summarizer/write path without poisoning the next Turn | Persist a late result or reuse aborted state |
 
-Fail-open here does not mean “always send the complete raw history.” Once history exceeds the model budget, the full raw prefix may itself be impossible to send. An initial V2 summary failure keeps a bounded raw tail and emits one visible `context_compaction_failed_open` note. A rolling failure may reuse the old checkpoint, but it never expands that checkpoint's coverage claim.
+Fail-open here does not mean “always send the complete raw history.” Once history exceeds the model budget, the full raw prefix may itself be impossible to send. An automatic pre-turn initial V2 summary failure leaves the original source-derived projection untouched; if that projection still exceeds the budget, the backend terminates with `context_budget_exhausted` before the failure-note path. Manual compaction records one visible `context_compaction_failed_open` note for the same failed outcome. A rolling failure may reuse the old checkpoint, but it never expands that checkpoint's coverage claim.
 
 The correct interpretation is:
 
@@ -501,26 +510,33 @@ Fifth, rolling summaries can accumulate lossy error. The original log still allo
 
 Read the current implementation from these locations:
 
-1. `packages/runtime/src/context-budget.ts`: high water, prefix/tail selection, checkpoint replay, and policy gates;
-2. `packages/runtime/src/history-compact-checkpoint.ts`: V2/V3 schemas, provider identity, digest, prefix match, lineage, and replay materialization;
-3. `packages/runtime/src/history-compact-summarizer.ts`: LLM continuation-summary prompt and rolling input;
-4. `packages/runtime/src/ai-sdk-backend.ts`: request-projection pipeline, manual compaction, writes, and fallback semantics;
-5. `packages/runtime/src/agent-run.ts`: durable `history_compact_checkpoint_recorded` event;
-6. `packages/runtime/src/history-compact-ledger.ts`: bounded-projection lookup, ledger recovery, and checkpoint selection;
-7. `packages/runtime/src/runtime-kernel.ts`: serialized checkpoint writes and manual-compaction lifecycle;
-8. `packages/storage/src/agent-run-store.ts`: commit ordering between canonical append and bounded event projection;
-9. `packages/runtime/src/context-budget-policy.ts`: model-capacity derivation and fixed Runtime policy;
-10. `packages/runtime/src/openai-codex-history-compactor.ts`: Codex compact-output validation and rolling provider-state input;
-11. `packages/runtime-host/src/server/execution-model-composition.ts`: default provider-specific compactor selection.
+1. `packages/runtime/src/context-budget.ts`: checkpoint-before-prune orchestration and context diagnostics;
+2. `packages/runtime/src/history-compaction.ts`: high-water estimation, safe prefix/tail selection, planning, and replay policy;
+3. `packages/runtime/src/history-compact-checkpoint.ts`: V2/V3 schemas, provider identity, digest, prefix match, lineage, and replay materialization;
+4. `packages/runtime/src/history-compact-summary-validation.ts`: the shared section, truncation, and large-fold size gates;
+5. `packages/runtime/src/history-compact-summarizer.ts`: LLM continuation-summary prompt, bounded repair, and rolling input;
+6. `packages/runtime/src/ai-sdk-compaction.ts`: compaction orchestration, malformed-input circuit, writes, and fallback semantics;
+7. `packages/runtime/src/ai-sdk-backend.ts`: prior-history request projection and provider materialization;
+8. `packages/runtime/src/agent-run.ts`: durable `history_compact_checkpoint_recorded` event;
+9. `packages/runtime/src/history-compact-ledger.ts`: bounded-projection lookup, ledger recovery, and checkpoint selection;
+10. `packages/runtime/src/runtime-kernel.ts`: serialized checkpoint writes and manual-compaction lifecycle;
+11. `packages/storage/src/agent-run-store.ts`: atomic canonical-event and bounded-projection persistence;
+12. `packages/runtime/src/context-budget-policy.ts`: model-capacity derivation and fixed Runtime policy;
+13. `packages/runtime/src/openai-codex-history-compactor.ts`: Codex compact-output validation and rolling provider-state input;
+14. `packages/runtime-host/src/server/execution-model-composition.ts`: default provider-specific compactor selection.
 
 Important tests include:
 
-- `history-compact-checkpoint.test.ts`: bounded 10K-event coverage, prefix digest, ledger recovery, and policy replay;
-- `history-compact-summarizer.test.ts`: Tool-bearing summarizer input, failure, and rolling updates;
-- `context-budget.test.ts`: high water, tail cap, Tool pair preservation, archive gates, and loaded blocks;
-- `ai-sdk-backend.test.ts`: same-request replacement, checkpoint reuse, fail-open, and manual compaction;
+- `history-compact-checkpoint.test.ts`: coverage metadata, prefix digest, summary admission, ledger recovery, projection repair, and policy replay;
+- `history-compaction.test.ts`: high-water estimation, safe prefix/tail selection, Tool pair preservation, rolling updates, and write gates;
+- `history-compact-summarizer.test.ts`: provider options, input fitting, structured-summary validation and repair, and rolling input;
+- `context-budget.test.ts`: canonical-ledger retention and checkpoint replay before stale Tool Result pruning;
+- `context-budget-mid-turn-policy.test.ts`: model-capacity derivation and fixed Runtime defaults;
+- `mid-turn-capacity-backend.test.ts`: persist-before-apply, fail-open/exhaustion detail, and active-turn retry bounds;
+- `openai-codex-history-compactor.test.ts`: unique complete provider-native compact-item admission;
+- `ai-sdk-backend.test.ts`: checkpoint reuse, malformed-input fingerprinting, fail-open, and manual compaction;
 - `session-manager.test.ts`: manual-compaction Run lifecycle, stop, and concurrency;
-- `agent-run-store.test.ts`: atomic ordering and repair safety for canonical events and bounded projections.
+- `sqlite-core-execution-store.test.ts`: SQLite AgentRun event durability and in-transaction derived-state ordering.
 
 ## Summary
 
diff --git a/docs/architecture/llm-compaction-events-log-projection-draft.zh-CN.md b/docs/architecture/llm-compaction-events-log-projection-draft.zh-CN.md
index 8fc9f520d1..6fc47609ed 100644
--- a/docs/architecture/llm-compaction-events-log-projection-draft.zh-CN.md
+++ b/docs/architecture/llm-compaction-events-log-projection-draft.zh-CN.md
@@ -7,7 +7,7 @@ counterpart: ./llm-compaction-events-log-projection-draft.md
 implementation_status: current
 document_status: draft
 translation_status: synced
-last_verified: 2026-08-14
+last_verified: 2026-08-28
 owners:
   - maka-backend
 ---
@@ -38,7 +38,7 @@ owners:
 
 本文主要讨论 **RuntimeEvent history compaction**：compactor 生成 continuation summary 或 provider-native compact state，checkpoint 覆盖一段安全的 RuntimeEvent 前缀，并在以后请求中用该投影替代前缀。手动、pre-turn、mid-turn 与 overflow 触发器共用同一个 planner 和 checkpoint transaction。本文不完整展开单个 Tool Result 的 active/stale prune；它们会缩小 provider messages，但不会形成另一套 LLM compaction 机制。
 
-本文描述截至 2026-08-23 的当前实现。ledger-backed checkpoint 中，schema V2 保存文本摘要，schema V3 保存 provider-native state。OpenAI Codex 订阅模型默认使用 Codex remote compaction V2，其他 provider 维持文本摘要行为。
+本文描述截至 2026-08-28 的当前实现。ledger-backed checkpoint 中，schema V2 保存文本摘要，schema V3 保存 provider-native state。OpenAI Codex 订阅模型默认使用 Codex remote compaction V2，其他 provider 维持文本摘要行为。
 
 ## 从一个长期会话开始
 
@@ -162,18 +162,21 @@ V2 中模型主要看到 `summary`；V3 中 provider 看到自己的 opaque comp
 1. 排除当前 `turnId`，得到 prior Runtime context；
 2. 准备 context budget policy；
 3. 加载最新且兼容的 ledger-backed checkpoint；
-4. 先处理 stale oversized tool results；
-5. 计算 history compact 的 high-water 与 retained tail；
-6. 校验已有 checkpoint 是否恰好匹配 source prefix；
-7. 如果旧 checkpoint 不足以覆盖新的 fold，调用 LLM 滚动生成 successor；
-8. V2 checkpoint 投影为 synthetic text RuntimeEvent；V3 checkpoint 则作为显式 projection metadata 传递，然后拼接未覆盖 raw tail；
-9. 建立 provider replay plan，最后才物化成 `ModelMessage[]`。
+4. 在 immutable RuntimeEvent 序列上校验并 replay 已有 checkpoint；
+5. 只对未覆盖的 projected remainder 执行 stale oversized Tool Result prune；
+6. 如果 projected history 仍超出预算，选择 safe prefix 与 retained tail；
+7. 如果旧 checkpoint 不足以覆盖新的 fold，调用 compactor 滚动生成 successor；
+8. successor 通过校验并 durable record 后才能使用；
+9. V2 checkpoint 投影为 synthetic text RuntimeEvent；V3 checkpoint 则作为显式 projection metadata 传递，然后拼接未覆盖 raw tail；
+10. 建立 provider replay plan，最后才物化成 `ModelMessage[]`。
 
-这条顺序说明两件事。
+这条顺序说明三件事。
 
-第一，compaction 发生在 **model-history projection** 内，而不是 RuntimeEvent append path 内。模型和工具已经产生的事件不会因为以后预算变化而改变。
+第一，checkpoint source matching 始终面对 immutable RuntimeEvent ledger。Stale Tool Result prune 只塑造未覆盖的 replay remainder，因此 recent-turn window 的移动不会改变 digest 所依据的字节，进而错误地让本来匹配的 checkpoint 失效。
 
-第二，checkpoint 也不是 canonical RuntimeEvent。coverage 与 tail selection 会把选中的 checkpoint 和投影后的 RuntimeEvents 一起显式返回。V2 checkpoint 还会物化为熟悉的 system-authored 文本块，供普通 replay planning 使用；兼容的 V3 checkpoint 不创建任何 synthetic 文本，由 provider materializer 直接在请求头部加入 assistant `openai.compaction` custom part。两种表示都不会伪装成原始交互事件写回 RuntimeEvent ledger。
+第二，compaction 发生在 **model-history projection** 内，而不是 RuntimeEvent append path 内。模型和工具已经产生的事件不会因为以后预算变化而改变。
+
+第三，checkpoint 也不是 canonical RuntimeEvent。coverage 与 tail selection 会把选中的 checkpoint 和投影后的 RuntimeEvents 一起显式返回。V2 checkpoint 还会物化为熟悉的 system-authored 文本块，供普通 replay planning 使用；兼容的 V3 checkpoint 不创建任何 synthetic 文本，由 provider materializer 直接在请求头部加入 assistant `openai.compaction` custom part。两种表示都不会伪装成原始交互事件写回 RuntimeEvent ledger。
 
 ## Trigger 在 compaction 开始前结束
 
@@ -206,7 +209,11 @@ LLM compaction 的任务是生成一份“让另一个 LLM 继续工作”的结
 - Next Steps；
 - Critical Context，包括精确路径、函数名、命令、结果和错误。
 
-Summarizer 会看到被新折叠的用户/模型文本与 tool call/result。Thinking 被有意排除。桌面端复用当前 Session 的 connection 和 model，并把 summary output cap 设为 4,096 tokens；checkpoint builder 随后还会按当前 compact policy 对最终 model-visible summary 再做 bounded rendering。
+Summarizer 会看到被新折叠的用户/模型文本与 tool call/result。Thinking 被有意排除。Runtime Host 复用当前 Session 选中的 connection、model 与 provider options，不额外设置 compaction-only output-token cap。如果 provider 以 output-length 结束，这份不完整 summary 会被拒绝。Checkpoint builder 保留完整的已接受 summary；replay gate 按完整 model-visible size 判断，而不是在生成后截断。
+
+文本 prompt 与 validator 共用一份 section template。新的 V2 summary 必须依次包含有实质内容的 `Goal`、`Progress`、`Next Steps` 与 `Critical Context`，不能结束在未闭合 fence 或其他 truncation marker 上，也不能相对 fold 过小：fold 超过 10,000 estimated tokens 时，summary 至少需要 200 estimated tokens。第一份 malformed completion 只有一次更严格的 repair request，checkpoint write gate 随后还会再次校验结果。
+
+Repair 之外的 malformed retry 也有上限。Runtime 为每个 Session backend 最多记住 16 个精确 malformed-input fingerprint，其中覆盖 connection、model、route、policy 与 input budget、request shape、previous checkpoint 和 folded source events。输入不变时直接 fail open，不再 dispatch provider；source 或配置变化后可以重试。Cancellation 不会触发这个 circuit。细分的 `malformed_summary_*` reason 会一直保留到 compaction diagnostics 与 terminal context-budget detail。
 
 但是 LLM 不决定以下事实：
 
@@ -309,16 +316,18 @@ Checkpoint 不是对任意事件集合的搜索摘要。它覆盖的是 compacta
 
 换句话说，**projection 本身也以事件形式持久化**。这不是循环定义：checkpoint event 不是被它覆盖的 source event，它记录的是“在某次 Run 中，系统接受了这个 projection”。原始 RuntimeEvents 仍然独立存在。
 
-AgentRunStore 还维护一个 bounded event projection，用于快速找到最近 checkpoint。写入顺序刻意遵守：
+AgentRunStore 还维护一个 bounded event projection，用于快速找到最近 checkpoint。Canonical event 与 derived projection 在同一个 SQLite transaction 中写入：
 
 ```text
-append canonical AgentRunEvent
-  → then update bounded checkpoint projection
+BEGIN write transaction
+  → insert canonical AgentRunEvent
+  → update bounded checkpoint projection
+COMMIT both
 ```
 
-如果 canonical append 失败，projection 不得保留。如果 projection 更新失败，canonical event 已经 durable，冷启动时可以从 Run ledgers 恢复。
+SQL statement 仍遵守 log-first 顺序，但两次写入之间不存在 partial durability boundary：任一 statement 失败，transaction 都会回滚两者。AgentRunEvent ledger 仍是 authority，是因为未初始化、legacy 或损坏的 projection 可以从中重建，而不是因为当前写入故意允许 event 与 projection 分开提交。
 
-这正是 log-first 系统常见的规则：索引可以缺失，事实提交不能由索引假装完成。
+这是 atomic commit 下的 log-first 规则：derived row 可以重建，也绝不能描述 canonical ledger 中不存在的事实。
 
 ## 冷启动恢复：Projection 坏了就从 Log 重建
 
@@ -348,13 +357,12 @@ flowchart TD
 
 ## Replay：Checkpoint 必须再次接受当前 policy 审判
 
-一个曾经合法的 checkpoint 不保证永远适合所有请求。模型可能切换，context window 可能变小，operator 也可能收紧 `maxBlockEstimatedTokens` 或 `maxEstimatedTokens`。
+一个曾经合法的 checkpoint 不保证永远适合所有请求。所选模型可能切换，context window 可能变小，Runtime 也可能根据当前 model facts 推导出更小的 `maxHistoryEstimatedTokens`。
 
-`evaluateHistoryCompactCheckpointReplay()` 是 checkpoint 进入模型历史的统一 policy gate。它重新计算 model-visible checkpoint tokens，并检查：
+`evaluateHistoryCompactCheckpointReplay()` 是 source-matched checkpoint 进入模型历史的统一 current-policy fit gate。它重新计算 V2 model-visible checkpoint estimate（V3 使用已记录的 estimate），并检查：
 
-- checkpoint 自身不超过单 block 上限；
-- checkpoint 不超过 compact projection 总上限；
-- checkpoint 与 replay tail 合计不超过当前 history budget。
+- checkpoint 与 replay tail 合计不超过当前 history budget；
+- 如果有 source projection 可供比较，replacement 必须严格小于该 source。
 
 只有 source match 与 current-policy fit 同时成立，projection 才能 replay。
 
@@ -383,7 +391,8 @@ Compaction 跨越 token estimation、LLM call、schema construction、durable ap
 | 失败位置 | 当前行为 | 不允许发生的事 |
 |---|---|---|
 | 未超过 high water | 保持原投影或普通预算裁剪 | 为了“提前优化”制造无来源摘要 |
-| LLM 返回空 summary | 不记录新 checkpoint；初次 compact 只保留安全 raw tail | 把空 projection 当作 covered history |
+| LLM 返回空 summary | 不记录新 checkpoint。自动 pre-turn compaction 保留原有的 source-derived projection；如果它仍然超出预算，则以 `context_budget_exhausted` 结束且不写入失败 note；手动 compaction 则记录一次可见的 `context_compaction_failed_open` note | 把空 projection 当作 covered history |
+| Text summary 格式不合法 | 只进行一次更严格的 repair，之后以细分 reason fail open；同一失败 fingerprint 不再 dispatch | 持久化不完整结构，或在相同 doomed input 上循环 |
 | Codex 没有返回唯一且合法的 compact item | 不记录新 checkpoint，走同一 fail-open 路径 | 持久化残缺或有歧义的 provider state |
 | Compaction input 在有界省略 Tool Result 后仍无法容纳 | 不发送 compaction request，走同一 fail-open 路径 | 要求 provider 压缩一条已经超出容量的请求 |
 | Rolling summarizer 失败 | 若旧 checkpoint 仍匹配且符合当前限制，则复用它并拼接能容纳的最新完整 raw Turns | 假装旧 checkpoint 已覆盖 newly evicted events |
@@ -393,7 +402,7 @@ Compaction 跨越 token estimation、LLM call、schema construction、durable ap
 | Bounded projection 损坏 | 从 canonical AgentRun ledger 恢复并修复 projection | 把缓存当成唯一事实源 |
 | 用户停止 manual compaction | 中止 summarizer/write 链路，不污染下一 Turn | 让迟到结果写入或复用 abort state |
 
-这里的 fail-open 不是“无论如何发送完整历史”。当历史已经超过模型预算时，完整 raw prefix 本身可能不可发送。V2 初次 summary 失败会保留 bounded raw tail，并写入一次可见的 `context_compaction_failed_open` note；rolling failure 可以复用旧 checkpoint，但绝不会扩大它的 coverage claim。
+这里的 fail-open 不是“无论如何发送完整历史”。当历史已经超过模型预算时，完整 raw prefix 本身可能不可发送。自动 pre-turn 的 V2 初次 summary 失败会原样保留 source-derived projection；如果该 projection 仍然超出预算，backend 会在失败 note 路径之前以 `context_budget_exhausted` 结束。手动 compaction 对同一失败结果写入一次可见的 `context_compaction_failed_open` note。Rolling failure 可以复用旧 checkpoint，但绝不会扩大它的 coverage claim。
 
 正确理解是：
 
@@ -501,26 +510,33 @@ LLM 在 summary 中写“测试已通过”仍然只是对 source events 的概
 
 当前实现可以从以下位置阅读：
 
-1. `packages/runtime/src/context-budget.ts`：high-water、prefix/tail selection、checkpoint replay 与 policy gate；
-2. `packages/runtime/src/history-compact-checkpoint.ts`：V2/V3 schema、provider identity、digest、prefix match、lineage 与 replay materialization；
-3. `packages/runtime/src/history-compact-summarizer.ts`：LLM continuation-summary prompt 与 rolling input；
-4. `packages/runtime/src/ai-sdk-backend.ts`：请求投影主链、manual compact、write/fallback 语义；
-5. `packages/runtime/src/agent-run.ts`：`history_compact_checkpoint_recorded` durable event；
-6. `packages/runtime/src/history-compact-ledger.ts`：bounded projection lookup、ledger recovery 与 checkpoint selection；
-7. `packages/runtime/src/runtime-kernel.ts`：checkpoint write serialization 与 manual compaction lifecycle；
-8. `packages/storage/src/agent-run-store.ts`：canonical append 与 bounded event projection 的提交顺序；
-9. `packages/runtime/src/context-budget-policy.ts`：model-capacity derivation 与固定 Runtime policy；
-10. `packages/runtime/src/openai-codex-history-compactor.ts`：Codex compact output 校验与 rolling provider-state input；
-11. `packages/runtime-host/src/server/execution-model-composition.ts`：默认 provider-specific compactor 选择。
+1. `packages/runtime/src/context-budget.ts`：checkpoint-before-prune orchestration 与 context diagnostics；
+2. `packages/runtime/src/history-compaction.ts`：high-water estimation、safe prefix/tail selection、planning 与 replay policy；
+3. `packages/runtime/src/history-compact-checkpoint.ts`：V2/V3 schema、provider identity、digest、prefix match、lineage 与 replay materialization；
+4. `packages/runtime/src/history-compact-summary-validation.ts`：共用的 section、truncation 与 large-fold size gate；
+5. `packages/runtime/src/history-compact-summarizer.ts`：LLM continuation-summary prompt、bounded repair 与 rolling input；
+6. `packages/runtime/src/ai-sdk-compaction.ts`：compaction orchestration、malformed-input circuit、write 与 fallback 语义；
+7. `packages/runtime/src/ai-sdk-backend.ts`：prior-history request projection 与 provider materialization；
+8. `packages/runtime/src/agent-run.ts`：`history_compact_checkpoint_recorded` durable event；
+9. `packages/runtime/src/history-compact-ledger.ts`：bounded projection lookup、ledger recovery 与 checkpoint selection；
+10. `packages/runtime/src/runtime-kernel.ts`：checkpoint write serialization 与 manual compaction lifecycle；
+11. `packages/storage/src/agent-run-store.ts`：canonical event 与 bounded projection 的 atomic persistence；
+12. `packages/runtime/src/context-budget-policy.ts`：model-capacity derivation 与固定 Runtime policy；
+13. `packages/runtime/src/openai-codex-history-compactor.ts`：Codex compact output 校验与 rolling provider-state input；
+14. `packages/runtime-host/src/server/execution-model-composition.ts`：默认 provider-specific compactor 选择。
 
 重点测试包括：
 
-- `history-compact-checkpoint.test.ts`：10K event bounded coverage、prefix digest、ledger recovery、policy replay；
-- `history-compact-summarizer.test.ts`：tool-bearing summary input、failure 与 rolling update；
-- `context-budget.test.ts`：high-water、tail cap、tool pair preservation、archive gate 与 loaded block；
-- `ai-sdk-backend.test.ts`：same-request replacement、checkpoint reuse、fail-open 与 manual compact；
+- `history-compact-checkpoint.test.ts`：coverage metadata、prefix digest、summary admission、ledger recovery、projection repair 与 policy replay；
+- `history-compaction.test.ts`：high-water estimation、safe prefix/tail selection、Tool pair preservation、rolling update 与 write gate；
+- `history-compact-summarizer.test.ts`：provider options、input fitting、structured-summary validation/repair 与 rolling input；
+- `context-budget.test.ts`：canonical-ledger retention，以及 checkpoint 在 stale Tool Result prune 前 replay；
+- `context-budget-mid-turn-policy.test.ts`：model-capacity derivation 与固定 Runtime defaults；
+- `mid-turn-capacity-backend.test.ts`：persist-before-apply、fail-open/exhaustion detail 与 active-turn retry bound；
+- `openai-codex-history-compactor.test.ts`：只接受唯一且完整的 provider-native compact item；
+- `ai-sdk-backend.test.ts`：checkpoint reuse、malformed-input fingerprint、fail-open 与 manual compact；
 - `session-manager.test.ts`：manual compaction 的 Run lifecycle、stop 与 concurrency；
-- `agent-run-store.test.ts`：canonical event 和 bounded projection 的原子顺序与 repair safety。
+- `sqlite-core-execution-store.test.ts`：SQLite AgentRun event durability 与 in-transaction derived-state ordering。
 
 ## 总结