round 2: pin checkpoint recognition at compile time

Move COMPACT_CHECKPOINT_SOURCE and isCompactCheckpointSource into a
cordis-free src/checkpoint.ts leaf, re-exported from the root so every
host-side consumer keeps its import. The client can then type-import the
leaf without reaching dsh-session's root, whose Context merge declares the
host sessions service and collides with the client's -- the dsh-commands/brand
shape. Renaming the plugin id now fails the client typecheck.

Also: keep recoverable summary text when a compact/summary mixes text with
other block types, and capture the seeded-history provenance seqs from the
pushes that produce them instead of deriving them by arithmetic.

packages/client/runtime/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/client/runtime/README.md
-README.md: 7bf8050ea988945bead491d02528906863b129a6
-README.zh.md: ff3c91dee956b2c65f0029c97c73d73f5a627b05
+README.md: 69576f1e23a34b83915d075c4120d04368c49f43
+README.zh.md: 7243a9119d9c669c76e8490bd271b2669568bff0

packages/client/runtime/README.md

@@ -18,7 +18,7 @@ SlotsService gives the renderer separate bare observables for `useSessions` and
 
 ## The human transcript
 
-`ConversationSnapshot.nodes` is the human transcript, not the model surface. `TranscriptAdapter` projects the raw window in log order — every append-origin surface event (`isAppendSurfaceEvent`) at its own log position, plus one `CompactionSummaryNode` marker per landed compaction checkpoint — and never consults surface order. A landed compaction therefore keeps the conversation it shadowed on the model side: the marker reports where the model stopped seeing that history instead of erasing it. Model-only replacement copies stay out: a pruned `tool/result` and a regenerated `assistant/message` rewrite one node for the model and mark no boundary. A checkpoint is a `user/message` carrying the compaction seam's plugin source that **replaced** a surface range; an appending plugin-sourced `user/message` is injected context, not a compaction. That source literal is restated locally because `dsh-compact` is unreachable from this program in both directions (the client purity gate rejects a value import; a type-only import collides the host `Context.sessions` merge) — `tests/compact-checkpoint-pin.spec.ts` is the drift trap.
+`ConversationSnapshot.nodes` is the human transcript, not the model surface. `TranscriptAdapter` projects the raw window in log order — every append-origin surface event (`isAppendSurfaceEvent`) at its own log position, plus one `CompactionSummaryNode` marker per landed compaction checkpoint — and never consults surface order. A landed compaction therefore keeps the conversation it shadowed on the model side: the marker reports where the model stopped seeing that history instead of erasing it. Model-only replacement copies stay out: a pruned `tool/result` and a regenerated `assistant/message` rewrite one node for the model and mark no boundary. A checkpoint is a `user/message` carrying the compaction seam's plugin source that **replaced** a surface range; an appending plugin-sourced `user/message` is injected context, not a compaction. The adapter's plugin literal is pinned to the seam's own declaration by a type-only import of the cordis-free [`dsh-compact/checkpoint`](../../compact/compact/README.md) leaf, so renaming it there fails `tsc` here; a **value** import of the package would fail the client purity gate, and the package **root** is unreachable even as a type (it reaches `dsh-session`'s root, whose `Context` merge collides the host `sessions` with this program's). `tests/compact-checkpoint-pin.spec.ts` covers the same drift behaviorally.
 
 Because the projection is log-ordered, the node array is seq-monotonic by construction: log-only `command/run` / `command/done` nodes splice in by seq, `Session` merges interrupted frozen nodes by their fractional seqs, and a window whose checkpoint cites a shadowed range outside it renders the marker with nothing logged. The marker's summary text comes from the checkpoint's `compact/summary` provenance; a window cut that left the provenance outside makes the row non-expandable rather than empty, and a later page that supplies it resolves the text. Performance contract: one append materializes one node, an event that changes no node keeps the previous array reference (a chunk storm costs nothing), and unchanged nodes keep their object identity.
 

packages/client/runtime/README.zh.md

@@ -18,7 +18,7 @@ SlotsService 分别为 renderer 提供 `useSessions` 与 `useWorkspaces` 的裸
 
 ## 人类对话记录
 
-`ConversationSnapshot.nodes` 是人类对话记录，不是模型 surface。`TranscriptAdapter` 按日志顺序投影原始窗口——每个 append 来源的 surface 事件（`isAppendSurfaceEvent`）落在它自己的日志位置上，外加每次落地的压缩检查点贡献一个 `CompactionSummaryNode` 标记——且从不查询 surface 顺序。于是一次落地的压缩会保留它在模型侧遮蔽掉的对话：标记报告模型从哪里开始看不见那段历史，而不是把它抹掉。仅模型可见的 replacement 副本不进入记录：被裁剪的 `tool/result` 和重新生成的 `assistant/message` 只为模型重写一个节点，不标记任何边界。检查点是携带压缩缝隙插件来源、且**替换**了一段 surface 范围的 `user/message`；一条 append 的插件来源 `user/message` 是注入上下文，不是压缩。该来源字面量在本地重述，因为 `dsh-compact` 在两个方向上都无法从本程序到达（客户端纯度门禁拒绝值导入；仅类型导入会与 host 的 `Context.sessions` 合并冲突）——`tests/compact-checkpoint-pin.spec.ts` 是漂移陷阱。
+`ConversationSnapshot.nodes` 是人类对话记录，不是模型 surface。`TranscriptAdapter` 按日志顺序投影原始窗口——每个 append 来源的 surface 事件（`isAppendSurfaceEvent`）落在它自己的日志位置上，外加每次落地的压缩检查点贡献一个 `CompactionSummaryNode` 标记——且从不查询 surface 顺序。于是一次落地的压缩会保留它在模型侧遮蔽掉的对话：标记报告模型从哪里开始看不见那段历史，而不是把它抹掉。仅模型可见的 replacement 副本不进入记录：被裁剪的 `tool/result` 和重新生成的 `assistant/message` 只为模型重写一个节点，不标记任何边界。检查点是携带压缩缝隙插件来源、且**替换**了一段 surface 范围的 `user/message`；一条 append 的插件来源 `user/message` 是注入上下文，不是压缩。适配器的插件字面量通过对无 cordis 的 [`dsh-compact/checkpoint`](../../compact/compact/README.md) 叶子做仅类型导入，钉在压缩缝隙自己的声明上：在那里改名会让此处 `tsc` 失败；而对该包做**值**导入会被客户端纯度门禁拒绝，包的**根**即便作为类型也无法到达（它会到达 `dsh-session` 的根，其 `Context` 合并会让 host 的 `sessions` 与本程序的冲突）。`tests/compact-checkpoint-pin.spec.ts` 从行为侧覆盖同一漂移。
 
 由于投影按日志顺序，节点数组天然按 seq 单调：仅日志的 `command/run` / `command/done` 节点按 seq 插入，`Session` 按分数 seq 归并被打断的冻结节点，而检查点所引范围落在窗口之外的窗口会渲染出标记且不打印任何日志。标记的摘要文本来自检查点的 `compact/summary` 溯源；窗口切分把溯源留在窗口外时该行不可展开而非空白，后续补上溯源的分页会解析出文本。性能契约：一次追加物化一个节点，不改变任何节点的事件保持上一次的数组引用（分片风暴零成本），未变化的节点保持其对象标识。
 

packages/client/runtime/src/client/sessions/conversation.ts

@@ -129,7 +129,14 @@ export interface CompactionSummaryNode {
   summary: string | null
 }
 
-/** Fallback for surface events this UI version does not know. */
+/**
+ * Fallback for surface events this UI version does not know: the documented
+ * default arm of `SessionEventMap`, which is merge-extensible, so the
+ * projection's switch cannot end in `assertNever`. No event produces this node
+ * today — `isAppendSurfaceEvent` admits only the four types in core's
+ * `SurfaceEventType`, and each has its own arm — and it exists so widening that
+ * set core-side degrades to a raw row instead of dropping the event silently.
+ */
 export interface UnknownSurfaceNode {
   kind: 'unknown'
   seq: number

packages/client/runtime/src/client/sessions/transcript-adapter.ts

@@ -12,25 +12,26 @@ import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
 // browser bundle cannot resolve; surface.ts has no Node dependencies.
 import { isAppendSurfaceEvent, isReplacementSurfaceEvent } from '@deepseek-ai/dsh-session/surface'
 import type { CommandId } from '@deepseek-ai/dsh-commands/brand'
+// Cordis-free leaf subpath (the dsh-commands/brand shape): the seam's own
+// declaration of the checkpoint source, reachable as a TYPE from this program.
+// The package ROOT is not — it reaches dsh-session's root, whose Context merge
+// declares the HOST `sessions: SessionStore` against this program's
+// `sessions: ISessions` (TS2717, the one-program-per-side rule in
+// docs/development.md).
+import type { COMPACT_CHECKPOINT_SOURCE } from '@deepseek-ai/dsh-compact/checkpoint'
 import type { ToolCallView, ToolEventView, ToolResultView } from '@deepseek-ai/dsh-client-connection/client'
 import type { CommandNode, CompactionSummaryNode, ConversationNode } from './conversation.ts'
 import { toAssistantBlocks } from './conversation.ts'
 
 /**
- * The compaction seam's checkpoint plugin, restated locally.
- *
- * `dsh-compact` cannot be reached from this program in any form. A VALUE import
- * fails the client purity gate (`packages/client/tsdown.client.ts`) and would
- * pull the cordis `Service` base into the browser bundle; a TYPE-ONLY import of
- * its `COMPACT_CHECKPOINT_SOURCE` fails typecheck, because `dsh-compact`'s root
- * reaches `dsh-session`'s root, whose `Context` merge declares the HOST
- * `sessions: SessionStore` against this program's `sessions: ISessions`
- * (`TS2717` — the one-program-per-side rule in docs/development.md). The
- * literal is pinned to the canonical const by
- * `tests/compact-checkpoint-pin.spec.ts`, which runs in the client TEST program
- * where that collision does not apply.
+ * The compaction seam's checkpoint plugin, pinned to the seam's own declaration
+ * at COMPILE time: renaming it there fails this annotation (`TS2322`). The
+ * import stays type-only because a value import would fail the client purity
+ * gate (`packages/client/tsdown.client.ts`) — cross-plugin value imports are
+ * forbidden in a browser bundle — while an erased type never reaches it.
+ * `tests/compact-checkpoint-pin.spec.ts` covers the same drift behaviorally.
  */
-const COMPACT_PLUGIN = 'compact'
+const COMPACT_PLUGIN: typeof COMPACT_CHECKPOINT_SOURCE.plugin = 'compact'
 
 /** In-window tool/call index entry (result-card backfill + runningCalls material). */
 export interface CallIndexEntry {
@@ -126,14 +127,20 @@ function isTranscriptEvent(event: SessionEvent): boolean {
   return isAppendSurfaceEvent(event) || isCompactCheckpoint(event)
 }
 
-/** Concatenated text of a `compact/summary` payload, or null when it carries no usable text. */
+/**
+ * Concatenated text of a `compact/summary` payload, or null when it carries no
+ * usable text. The payload is a `ContentBlock[]` whose union is
+ * merge-extensible, so a non-text block is skipped rather than discarding the
+ * text beside it; a payload with no text block at all falls to null through the
+ * empty check.
+ */
 function compactSummaryText(event: SessionEvent): string | null {
   const summary = (event.data as unknown as { summary?: unknown }).summary
-  if (!Array.isArray(summary) || summary.length === 0) return null
+  if (!Array.isArray(summary)) return null
   let text = ''
   for (const block of summary as readonly unknown[]) {
     const candidate = block as { type?: unknown; text?: unknown }
-    if (candidate.type !== 'text' || typeof candidate.text !== 'string') return null
+    if (candidate.type !== 'text' || typeof candidate.text !== 'string') continue
     text += candidate.text
   }
   return text.trim() === '' ? null : text

packages/client/runtime/tests/compact-checkpoint-pin.spec.ts

@@ -1,17 +1,15 @@
 /**
- * Drift trap for the compaction-checkpoint recognition rule.
+ * Behavioral half of the compaction-checkpoint drift trap.
  *
- * `TranscriptAdapter` restates the compaction seam's checkpoint source as a
- * local literal because it cannot import `dsh-compact` in any form: a VALUE
- * import fails the client purity gate, and a TYPE-ONLY import fails typecheck —
- * `dsh-compact`'s root reaches `dsh-session`'s root, whose cordis `Context`
- * merge declares the HOST `sessions: SessionStore` against the client program's
- * `sessions: ISessions` (`TS2717`). This spec runs in the client TEST program,
- * which does not carry that collision, and it is the only thing keeping the two
- * implementations from drifting: it drives the adapter with a checkpoint built
- * from the canonical `COMPACT_CHECKPOINT_SOURCE` itself, so renaming the seam's
- * plugin fails HERE instead of silently deleting every compaction marker from
- * the web transcript.
+ * `TranscriptAdapter` pins its plugin literal to the seam's own declaration at
+ * compile time through a type-only import of `dsh-compact/checkpoint`, so
+ * renaming the seam's plugin already fails `tsc`. This spec covers the same
+ * drift from the other side — end to end through the adapter, driving it with a
+ * checkpoint built from the canonical `COMPACT_CHECKPOINT_SOURCE` **value** and
+ * checking the seam's own predicate agrees. It runs in the client TEST program,
+ * which can value-import the package root; a `packages/client/*` package
+ * program cannot, because that root reaches `dsh-session`'s root and collides
+ * the host `Context.sessions` merge (`TS2717`).
  */
 
 import { COMPACT_CHECKPOINT_SOURCE, isCompactCheckpointSource } from '@deepseek-ai/dsh-compact'

packages/client/runtime/tests/transcript-adapter.spec.ts

@@ -225,7 +225,7 @@ describe('TranscriptAdapter', () => {
 
     it.each([
       ['absent provenance', undefined],
-      ['malformed summary blocks', compactSummary(1, [{ type: 'image', data: 'nope' }])],
+      ['text-less summary blocks', compactSummary(1, [{ type: 'image', data: 'nope' }])],
       ['a whitespace-only summary', compactSummary(1, [{ type: 'text', text: '   ' }])],
       ['an empty summary array', compactSummary(1, [])],
       ['a non-array summary', compactSummary(1, 'plain string')],
@@ -240,6 +240,19 @@ describe('TranscriptAdapter', () => {
       ])
     })
 
+    it('keeps the text of a mixed-block summary, skipping the blocks it cannot render', () => {
+      // ContentBlock is merge-extensible and the payload type is ContentBlock[],
+      // so a non-text block must not discard recoverable text beside it.
+      const adapter = new TranscriptAdapter()
+      adapter.reset([
+        compactSummary(1, [{ type: 'text', text: '可用摘要' }, { type: 'image', data: 'nope' }]),
+        checkpoint(2, 1, { start: 0, end: 0, sourceEventSeqs: [1, 0] }),
+      ])
+      expect(adapter.nodes()).toEqual([
+        { kind: 'compaction', seq: 2, time: 1_700_000_000_002, summary: '可用摘要' },
+      ])
+    })
+
     it('leaves the summary null when the checkpoint records no provenance at all', () => {
       const adapter = new TranscriptAdapter()
       adapter.reset([at(2, {

packages/client/runtime/tsconfig.json

@@ -26,6 +26,9 @@
     {
       "path": "../../ui/commands"
     },
+    {
+      "path": "../../compact/compact"
+    },
     {
       "path": "../../session-projection/session-projection"
     },