Merge worktree-hooks-b-bash-seam into worktree-hooks-c-interception
Bring the interception-seams branch onto current master (via A→B). The substantive reconciliation is master's compaction `agent/pre-step` serial seam meeting C's interception seams: - types.ts: keep BOTH master's `agent/pre-step` AND C's new interception events (`agent/prompt-submit`, `agent/session-start`, `agent/turn-continuation`→ `ContinuationDecision`); drop the turn-mirror declarations (removed on A). - loop.ts: the merged per-turn order is `turn/start` → per queued msg `agent/prompt-submit` (rewrite/inject/block) → (fully-blocked ⇒ zero-step `rejected`) → per step: drain steering → assemble system prompt → `agent/pre-step` (compaction, OUTSIDE the step) → `step/start` → single `deriveMessages()` → model → tools/pre-execute·dispatch·post-execute. No turn-mirror emits; `closeTurn()` is the A-simplified single-call form. - Docs (architecture, core.md, agent/agent-loop READMEs, catalog) reconciled to show C's interception seams alongside `agent/pre-step`, no turn/step mirrors. - rfc/README: dropped the stale `proposed/` compaction row (master moved that RFC to implemented/); kept C's new `pre-tool-input-rewrite` proposed row. - interception.spec.ts: migrated its two `agent/turn-end` reason collectors to the `turn/end` session event, and ADDED a cross-test proving a `prompt-submit` rewrite + additionalContext is VISIBLE to an `agent/pre-step` listener on the same turn — pinning the merged seam ordering (compaction sees the post-prompt-submit surface, not stale history).
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Tianyi Cui
@@ -27,7 +27,7 @@ The mapping between ACP and existing harness seams — each row names the seam a
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| `session/new {cwd, mcpServers, additionalDirectories}` → `{sessionId}` | the `dsh-agent` create factory (see Dependency note + Plan) | the seam must accept `{ sessionId, meta }` so the ACP-generated `sessionId` becomes the live/persisted session id and the validated `cwd` is attached as the `SessionHeader` (today `AgentLoop.create(id)` hardcodes `${id}-session` and takes no metadata); reject a 2nd session (single-session MVP, see [ACP multi-session](2026-06-14-acp-multi-session.md)); `cwd` validated (require absolute) — any absolute cwd is honored: it becomes the session's `SessionHeader.cwd` and the default bash workdir (per-session cwd, see § Deferred → RESOLVED), so the server need not launch in the workspace; non-empty `mcpServers` and `additionalDirectories` are rejected for the MVP because silently ignoring requested servers/roots would desync the client's tool and filesystem-scope UI |
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| `session/load {sessionId, cwd, mcpServers, additionalDirectories}` | the `dsh-agent` resume factory ([session persistence](../../implemented/architecture/2026-06-14-session-persistence.md) + Dependency note) | load `{ meta, events }`, seed the session, re-derive history via `deriveMessages()`, replay prior turns to the client as `session/update` per the ACP load contract; `mcpServers` and `additionalDirectories` rejected as in `session/new` |
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| `session/prompt {prompt}` | `agent.send()` (idle) | text blocks → `TextBlock`; reject image/audio per advertised capabilities; one in-flight prompt per session |
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| resolve `session/prompt` → `{stopReason}` | `agent/turn-end` (extended, see Plan) | map the harness kebab `TurnEndReason` to the ACP snake_case `StopReason` wire enum: `completed`→`end_turn`, `max-tokens`→`max_tokens`, `aborted`(cancel)→`cancelled`, plus `refusal`/`max_turn_requests` when applicable; honor the batch-into-one-turn and send-not-synchronously-running settle semantics |
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| resolve `session/prompt` → `{stopReason}` | the `turn/end` `session/event` (its `reason`) | map the harness kebab `TurnEndReason` to the ACP snake_case `StopReason` wire enum: `completed`→`end_turn`, `max-tokens`→`max_tokens`, `aborted`(cancel)→`cancelled`, plus `refusal`/`max_turn_requests` when applicable; honor the batch-into-one-turn and send-not-synchronously-running settle semantics |
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| `session/update: agent_message_chunk` | `agent/stream-chunk` `text-delta` only | do NOT also emit on `block-end(TextBlock)` — it carries the fully-assembled block and would duplicate the streamed text |
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| `session/update: agent_thought_chunk` | `agent/stream-chunk` `reasoning-delta` | |
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| `session/update: tool_call` (pending→in_progress) | `session/event` `tool/call` | demux via a Session→sessionId map; `kind` inferred from the tool name |
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@@ -46,7 +46,7 @@ Lifecycle and disposal: the connection, listeners, and in-flight permission prom
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1. Package scaffold `packages/ui/acp/` per [the cookbook](../../../cookbook/adding-a-package.md); add `@agentclientprotocol/sdk` and `zod`. Add the abstract create/resume factory to `dsh-agent` (the interface) so the bridge can `inject: ['agents', 'sessions', 'tools', 'sessionPersistence']` without depending on the concrete loop; `sessionPersistence` is required because `session/load` advertises `loadSession: true`. (Fallback only if the factory is judged not worth it: inject `agentLoop` directly and record the architecture-rule exception in `docs/architecture.md`.)
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2. Connection plus `initialize`/`session/new`: wire `AgentSideConnection` to stdin/stdout; protocolVersion negotiation; the single-session guard; create the live session through the new `{ sessionId, meta }` factory seam (so the ACP `sessionId` and validated `cwd` become the session's id and header); the `sessionId↔agent` and `Session↔sessionId` maps.
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3. Internal edit — turn-end reason fidelity (sanctioned: edit internals to fit ACP). Extend `TurnEndReasonMap` in the proper places: (a) declaration-merge a `max-tokens` variant in the owning package (`packages/core/session/src/types.ts`, alongside `completed|aborted|error|disposed`) — add `max-tokens` because `FinishReasonMap` produces it (DeepSeek maps `length` → `max-tokens`); do not add `refusal`, since no current adapter produces it (unknown DeepSeek finish reasons collapse to `error`), but leave a comment in `TurnEndReasonMap` noting `refusal` should be added when an adapter first emits it (`FinishReasonMap` is merge-extensible); (b) make `agent-loop`'s `loop.ts` populate the reason from the model `finish` chunk — `assembler.finish` lives inside `runStep`, so `runStep` must return it up to `runTurn`, and the rule is "the last step's finish reason wins, but any `max-tokens` in the turn surfaces as `max-tokens`"; (c) no consumer exhaustively switches over `TurnEndReason` today (the invariants plugin switches on `SessionEventType`, and `deriveMessages` ignores `turn/end`), so adding `max-tokens` is a non-breaking extension — but recheck before landing; (d) update [docs/architecture.md](../../../architecture.md) (the CI-verified loop-lifecycle/event-taxonomy doc) and the affected package READMEs/JSDoc (`dsh-session`, `dsh-agent`, `dsh-agent-loop`) per the repo doc-sync policy. This replaces a fragile "observe the finish chunk in the bridge" hack with a real, documented contract.
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4. Prompt-turn streaming plus load: translate `agent/stream-chunk` and `session/event` into `session/update`; resolve `session/prompt` on settle, mapping the harness `TurnEndReason` to the ACP `StopReason` wire enum (`completed`→`end_turn`, `max-tokens`→`max_tokens`, `aborted`→`cancelled`) — a small total function with a test asserting the exact wire strings, since the SDK rejects an unknown `stopReason`. Concrete correlation, since the loop batches queued messages into one turn and `send()` does not synchronously flip to running: install listeners before `send()`; gate on an observed `agent/turn-start` (confirms work was accepted) then resolve on the next `agent/turn-end`; reject an empty/whitespace prompt up front rather than calling `send()` (no turn would ever start, so the RPC would hang). Implement `session/load` on the session-persistence resume seam.
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4. Prompt-turn streaming plus load: translate `agent/stream-chunk` and `session/event` into `session/update`; resolve `session/prompt` on settle, mapping the harness `TurnEndReason` to the ACP `StopReason` wire enum (`completed`→`end_turn`, `max-tokens`→`max_tokens`, `aborted`→`cancelled`) — a small total function with a test asserting the exact wire strings, since the SDK rejects an unknown `stopReason`. Concrete correlation, since the loop batches queued messages into one turn and `send()` does not synchronously flip to running: install the `session/event` listener before `send()`; capture the prompt's owning turn from its `turn/start` record, then resolve on that turn's `turn/end` (with `agent/status` idle/disposed as a fallback); reject an empty/whitespace prompt up front rather than calling `send()` (no turn would ever start, so the RPC would hang). Implement `session/load` on the session-persistence resume seam.
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5. Permission gate: a single `tools/execute` listener registered with `prepend: true`, owning a `WeakMap<Agent, sessionId>` of bridge-created agents; no-op (`next()`) for unowned/no-agent calls; for owned calls → `session/request_permission` → allow (`next()`) / veto; settle the stored resolver exactly once on outcome, cancel, or connection close.
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6. Example wiring (extract a shared base). `@cordisjs/plugin-include` is itself a plugin entry that resets `ctx.baseUrl` and loads a path, so a child `cordis.yml` can nest-include a shared base; the extraction is safe because every dependent plugin declares `inject` (loader groups initialize via `Promise.all`, so YAML order is NOT the dependency mechanism — never rely on it). Extract the provider/tool core (`llm, sessions, system-prompt, tools, agents, invariants, llm-deepseek, bash-local, tool-bash`) into `examples/base.yml`; have both `coding-agent` and a new `examples/acp-agent/` include it and add their own UI plugin plus logger. Keep `agent-loop` per-example (NOT in the base): `AgentLoop` creates its configured agents in its constructor, and the two examples disagree — `coding-agent` needs a pre-created `main` (its `stdio-chat` calls `ctx.agents.get('main')`), while `acp-agent` must pre-create none (ACP `session/new` creates agents). So `coding-agent` declares `agent-loop` with `agents: [{ id: main, … }]` and `acp-agent` with `agents: []`. `acp-agent` loads `dsh-session-persistence-jsonl` (from [session persistence](../../implemented/architecture/2026-06-14-session-persistence.md) — required for `session/load`), omits the stdout logger (see Risks), and adds `pnpm run demo:acp` plus the Zed `agent_servers` snippet.
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7. Tests (the repo cares a lot here): a property-based test for the protocol shape (precedent: [property-based testing](../../implemented/testing/2026-06-11-property-based-testing.md)) — fuzz arbitrary harness event sequences and assert ACP-stream invariants (never a `tool_call_update` before its `tool_call`; exactly one `session/prompt` resolution per prompt; monotonic, well-formed ordering; `stopReason` in the legal set); codec unit tests over an in-memory `Duplex` pair (drive `AgentSideConnection` without a subprocess; assert exact frames for `initialize`, `session/new`, a full prompt turn); the mandatory HMR-safety test (dispose the fiber; assert the connection closed, all `ctx.on` listeners gone, any in-flight `request_permission` settled); failure-path tests (connection closes mid-stream; closes with a permission pending; a notification `send()` rejects but the turn survives; `finish{kind:'error'|'aborted'}`; a `tools/execute` throw with no `tool/result`; a second `session/new` rejected; a `session/prompt` while one is in flight; an empty prompt rejected without hanging; a `session/load` re-derives identical history and replays it); and an e2e (`*.e2e.ts`, self-skips without `DEEPSEEK_API_KEY`) that boots `examples/acp-agent`, connects a `ClientSideConnection`, sends a real prompt, owns and disposes the harness in `afterEach`, and verifies the world (files on disk), not the agent's self-report.
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@@ -1,59 +0,0 @@
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# RFC: Compaction as a capability seam (abstract contract + basic backend)
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Status: proposed (2026-06-18)
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## Context
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A long-running agent conversation grows without bound. As the event log accumulates turns, the derived message history eventually approaches the model's context window — the model then truncates mid-response (`max-tokens`) or degrades. **Compaction** is the mitigation: replace a run of older history with a concise summary, keeping recent context intact.
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The [session surface](../../implemented/architecture/2026-06-18-session-surface.md) was built as the foundation for exactly this — a linked list over the event log with a `surfaceOp: { op: 'replace', start, end }` operation purpose-built to shadow a range of nodes and insert a replacement, with `sourceEventSeqs` recording provenance so the decision replays deterministically. What remained was the plugin that *decides what to compact and produces the summary*.
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Two forces shape the design. First, compaction is **swappable**: token counting can be a char/4 heuristic or a real tokenizer, and summarization can be a model call, a template, or a remote service — these vary independently of *when* and *which range* to compact. Second, a later commit (`ce43c25`) closed `SurfaceEventType` to five event types (`user/message`, `assistant/message`, `tool/result`, `context/message`, `steering/message`); only those may carry `surfaceOp`. A bespoke `compaction/*` event therefore **cannot** itself appear on the surface — the compiler rejects `surfaceOp` on it and the invariants plugin rejects it at runtime.
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## Decision
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### Compaction is a capability seam, split interface / implementation
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Per the [capability-seams RFC](../../implemented/architecture/2026-06-13-capability-seams.md), compaction ships as separate packages so the contract, the algorithm, and (later) the consumer surface evolve independently:
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1. **Interface** — `@deepseek-ai/dsh-compact`: an abstract `CompactService` owning the `ctx.compact` key, the `CompactionResult` vocabulary, and the `compact/*` session events. It declares `compactIfNeeded()` and `compactRegion()` as **abstract** — the contract states *what* compaction does, not *how*.
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2. **Implementation** — `@deepseek-ai/dsh-compact-basic`: a concrete `BasicCompactService` that owns the entire algorithm — token estimation (char/4 + per-block overhead), the tail→head retention walk, summarization via `ctx.llm.generate()`, the surface replacement, the lock, and the `agent/request` auto-compaction listener. A tokenizer-based or template-based backend is a sibling package (or a subclass overriding the two protected estimation/summarization hooks).
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3. **Consumer** — deferred. A `/compact` tool and slash command will `inject: ['compact']` and call the contract; they are intentionally out of scope here so the seam settles first.
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### The contract depends on `dsh-session` and `dsh-llm` — a deliberate deviation
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The capability-seams RFC states the interface package "depends only on cordis" (true of `dsh-bash`, whose vocabulary is self-contained). Compaction **cannot** honor that: its verbs are defined *over* a `Session` (`compactRegion(session, start, end)`) and its output *is* the content vocabulary (`CompactionResult.summary: ContentBlock[]`). There is no way to express the contract without naming `Session`/`SessionEvent` (from `dsh-session`) and `ContentBlock` (from `dsh-llm`).
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This is not a coupling smell — it is the contract's domain. The "only cordis" guidance was always shorthand for "the interface depends only on what the contract genuinely names, and never on an implementation." `dsh-session` and `dsh-llm` are themselves interface/vocabulary packages, not implementations; `dsh-compact` still imports no backend. The seam's real invariant — *consumers and implementations evolve independently behind an abstract service* — holds intact. We record the deviation here so a future reader doesn't mistake it for an accident or "fix" it by smuggling `Session` behind an opaque handle.
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### Abstract `compactIfNeeded` / `compactRegion`, algorithm in the backend
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An earlier draft put the full algorithm (the retention walk, token-summing, text extraction) as concrete methods on the interface, with only `estimateContentTokens()` and `summarize()` abstract. That recouples the contract to one strategy: a backend that wants a different retention policy (e.g. turn-count instead of token-budget) or a different event-sequencing would have to fight inherited concrete code. Making both core methods abstract puts every *how* decision in the backend, where it belongs, and keeps the interface a pure statement of *what*. The backend remains internally factored — `estimateContentTokens()` and `summarize()` are `protected` hooks a sub-backend can override without reimplementing the walk — but that factoring is the backend's private concern, not the contract's.
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### Surface replacement: `compact/*` events are log-only; one `user/message` carries the summary
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Because `SurfaceEventType` is closed, the summary cannot ride on a `compact/*` event. The backend instead appends a **single `user/message`** with `surfaceOp: { op: 'replace', start, end }` whose `content` is the summary `ContentBlock[]` and whose `sourceEventSeqs` covers the shadowed nodes *and* the bookkeeping events. The `compact/*` events are pure log records (lock + provenance), never on the surface. The surface mutation sits **inside** the lock — `compact/end` is the last event appended:
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```
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compact/start → log-only. Acquires the lock.
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[summarize older range via the backend]
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compact/summary → log-only. Provenance: summary, range, shadowed seqs, token count.
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user/message → surfaceOp { op:'replace', start, end }. THE surface mutation.
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deriveMessages() renders it as a user-role message.
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compact/end → log-only. Releases the lock.
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```
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Ordering the surface mutation **before** `compact/end` is deliberate: `session.append()` commits one event at a time, so there is no multi-event transaction to make the sequence atomic. Releasing the lock last converts the crash window from *silent corruption* (a `compact/end` that claims compaction finished while the surface was never shadowed) into a *detectable orphaned lock* (a `compact/start` with no matching `compact/end`), which a persistence backend already detects on reload. A `session/event` listener on `compact/end` likewise never sees the lock free before the replacement has landed.
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`deriveMessages()` then yields `[summary_as_user_message, ...retained_nodes]`. An alternative — extending `SurfaceEventType` to admit a `compact/*` type — was rejected: the closed union is a deliberate safety boundary (only message-producing events reach the model), and a summary genuinely *is* user-role context, so reusing `user/message` is honest rather than a workaround.
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### Blocking via a log-recorded lock, not a mutex
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Compaction must be serialized: no second compaction starts before the first finishes, and no ordinary events interleave the slow summarization. Rather than an in-memory mutex (invisible to replay, lost on crash), the lock **is** the log: `compactRegion` refuses to start if the last `compact/start` has no matching `compact/end` after it. `compact/start` is appended first (fast, synchronous), the slow model call runs, then the `compact/summary` and `user/message` replacement land, and only then is `compact/end` appended — in a `catch` that records the error, so a failed summarization can never wedge the lock. Because the backend runs compaction synchronously inside the `agent/request` waterfall, the loop is single-threaded for that window; the lock additionally gives observability and lets a persistence backend detect an orphaned `compact/start` on reload.
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## Consequences
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- **New packages**: `packages/compact/compact` (interface) and a sibling `compact-basic` (backend) under `packages/compact/`, wired into the three root tsconfigs. The consumer tier is deferred.
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- **`SessionEventMap`** gains `compact/start` / `compact/summary` / `compact/end` by declaration merging (merge-extensible); `SurfaceEventType` is **not** touched. These are session events, not cordis `Events`, so the event-taxonomy gate needs no entry.
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- **No changes** to `dsh-session`, `dsh-invariants`, or `dsh-agent-loop`: the surface replace op, the surface-metadata runtime guard, and the `agent/request` waterfall all already exist. Compaction is a pure plugin on documented seams.
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- The capability-seams convention gains a second reference beyond bash, and a documented case where "interface depends only on cordis" relaxes to "depends only on interface/vocabulary packages the contract genuinely names." On acceptance, [AGENTS.md](../../../../AGENTS.md) § Conventions and [architecture.md](../../../architecture.md) § "Capability seams" should note this relaxation.
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@@ -1,31 +0,0 @@
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# RFC: Stop mirroring durable boundaries as agent events
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Status: proposed
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## Problem
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The loop records the canonical transcript in `SessionEvent` and also emits a parallel set of live `agent/*` mirror events: `agent/turn-start`, `agent/turn-end`, `agent/step-start`, `agent/step-end`, `agent/stream-chunk`, and `agent/steering`. The mirrors make consumers choose between two sources of truth. ACP already chose the session log for the editor-facing transcript because a throwing peer listener can prevent later `agent/*` listeners from observing a boundary, while the session event was already appended. The stdio UI is the only production consumer that still renders turn boundaries and the token stream from the mirror events; it already renders tool calls and results from `session/event`.
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This duplication is not free. Every lifecycle change has to update the session event, the mirror event, docs, invariants, tests, and snapshot expectations. The duplicate boundary events also make failure ordering subtle: a turn can be durably closed before a live `agent/turn-end` listener runs, so a post-boundary listener failure has no valid in-log position left and must be reported out of band.
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## Proposal
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Make `session/event` the live transcript stream. Consumers that render turns, tool calls, tool results, assistant messages, and durable boundaries subscribe to `session/event` and derive their UI from the same event vocabulary persistence uses. Keep agent lifecycle/control events that are not transcript data: `agent/created`, `agent/disposed`, `agent/status`, `agent/error`, and `agent/queued`. `agent/queued` is an inbox acknowledgement rather than a transcript mirror: it fires before any durable event exists, and cancelled queued work may never enter the log.
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Remove the duplicate durable-boundary mirrors from the agent event taxonomy. If a UI wants an agent handle from a session event, it can keep a small map from session id to agent built from `agent/created`/`agent/disposed`, or the registry can offer an explicit lookup. The canonical record remains the event-sourced session log.
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## Acceptance criteria
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- ACP and stdio render transcript content from `session/event`.
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- `agent/turn-start`, `agent/turn-end`, `agent/step-start`, `agent/step-end`, and `agent/steering` are removed or reduced to private implementation details.
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- `agent/queued` is either retained and documented as live-only inbox/control state, or deleted in a separate proposal that names the queue-acknowledgement capability loss.
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- Tests assert the persisted event stream, not a second mirror stream, for turn and step ordering.
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- Documentation presents `SessionEvent` as both the durable source and the live transcript feed.
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## What we give up
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A plugin can no longer observe turn/step boundaries from a convenient `Agent`-first event. It must either subscribe to `session/event` or maintain a session-to-agent association. That is an acceptable trade: transcript consumers should not depend on a second event feed that can drift from the durable log.
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## Related
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Because high-fidelity `assistant/chunk` persistence remains load-bearing, `agent/stream-chunk` can be evaluated as another mirror of durable session data rather than as the only token stream. If a future proposal moves chunks out of the canonical log, `agent/stream-chunk` would need a fresh decision as a deliberately live-only UI signal.
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