Merge PR #138 into simplification RFC sweep

# Conflicts:
#	docs/rfc/README.md

docs/rfc/proposed/feature/2026-06-14-acp-agent-client-protocol.md

@@ -7,7 +7,7 @@ Status: proposed
 
 ## Problem
 
-The coding agent is reachable only through the readline `stdio-chat` plugin: it reads lines from stdin, calls `agent.send()`, and prints `agent/stream-chunk` to stdout. There is no structured protocol, so the agent cannot be embedded in an editor — no streaming render, no tool-call display, no permission UI, no resumable sessions.
+The coding agent is reachable only through the readline `stdio-chat` plugin: it reads lines from stdin, calls `agent.send()`, and prints the assistant token stream (`session/event` `assistant/chunk`) to stdout. There is no structured protocol, so the agent cannot be embedded in an editor — no streaming render, no tool-call display, no permission UI, no resumable sessions.
 
 Editors are converging on the Agent Client Protocol (ACP), which Zed and others speak: JSON-RPC 2.0 over newline-delimited stdio, modeled on the Language Server Protocol. An editor boots the agent as a subprocess and exchanges `initialize` / `session/new` / `session/prompt`, rendering streamed `session/update` notifications and `session/request_permission` prompts. The goal is for the agent to be a drop-in ACP server — implement the protocol once and run in any ACP client, with no per-editor glue.
 
@@ -15,7 +15,7 @@ This RFC has a hard prerequisite on [session persistence](../../implemented/arch
 
 ## Proposal
 
-A new plugin package `@deepseek-ai/dsh-acp` — a client-driver / UI plugin, the structured analogue of `stdio-chat`. It is NOT a change to the loop and NOT an [capability seams](../../implemented/architecture/2026-06-13-capability-seams.md) interface/implementation/consumer capability split; it consumes the existing `agent/*` event taxonomy and the `tools/execute` waterfall.
+A new plugin package `@deepseek-ai/dsh-acp` — a client-driver / UI plugin, the structured analogue of `stdio-chat`. It is NOT a change to the loop and NOT an [capability seams](../../implemented/architecture/2026-06-13-capability-seams.md) interface/implementation/consumer capability split; it consumes the existing `agent/*` event taxonomy and the `tools/pre-execute`/`tools/post-execute` waterfalls.
 
 It depends on the official `@agentclientprotocol/sdk` (the `AgentSideConnection` class) — Apache-2.0, actively versioned. The SDK declares a `zod` peer dependency and imports `zod/v4` at runtime, so `packages/ui/acp` must declare `zod` itself (per the workspace dependency constraints). This is the renamed successor to `@zed-industries/agent-client-protocol`, which is now deprecated on npm.
 
@@ -27,9 +27,9 @@ The mapping between ACP and existing harness seams — each row names the seam a
 | `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 |
 | `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` |
 | `session/prompt {prompt}` | `agent.send()` (idle) | text blocks → `TextBlock`; reject image/audio per advertised capabilities; one in-flight prompt per session |
-| 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 |
-| `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 |
-| `session/update: agent_thought_chunk` | `agent/stream-chunk` `reasoning-delta` | |
+| 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 |
+| `session/update: agent_message_chunk` | `session/event` `assistant/chunk` `text-delta` only | do NOT also emit on `block-end(TextBlock)` — it carries the fully-assembled block and would duplicate the streamed text |
+| `session/update: agent_thought_chunk` | `session/event` `assistant/chunk` `reasoning-delta` | |
 | `session/update: tool_call` (pending→in_progress) | `session/event` `tool/call` | demux via a Session→sessionId map; `kind` inferred from the tool name |
 | `session/update: tool_call_update` (completed/failed) | `session/event` `tool/result` | a throwing `tools/execute` yields NO `tool/result` → fail the pending tool UI from `agent/error`/turn-end |
 | `session/request_permission {sessionId, toolCall, options}` | prepended `tools/execute` listener | no-op unless `exec.agent` is ACP-owned; await the outcome; `selected/allow_*` → `next()`; `reject_*`/`cancelled` → veto `ToolExecutionResult{isError}` |
@@ -46,7 +46,7 @@ Lifecycle and disposal: the connection, listeners, and in-flight permission prom
 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`.)
 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.
 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.
-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.
+4. Prompt-turn streaming plus load: translate `session/event` (the `assistant/chunk` token stream plus boundaries and tool activity) 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.
 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.
 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.
 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.

docs/rfc/proposed/feature/2026-06-15-optional-code-mode.md

@@ -55,7 +55,7 @@ These are illustrations of the seam's reach, **not commitments** — the MVP shi
 
 **3c. The single tool — `run_code`.** Registered normally in `ctx.tools` with one parameter `{ code: string (required) }`. Because it is an ordinary tool, the unchanged loop dispatches it through the normal path — this is the crux of "zero loop changes." Its `execute(args, exec)`:
 
-1. Builds the SDK bindings. For each real tool, an async `invoke(callArgs)` that **checks `exec.signal?.aborted` (throwing if set) before and after** calling `ctx.tools.execute({ callId: <deterministic sub-id>, name, arguments: callArgs, agent: exec.agent, signal: exec.signal })`, then maps the resulting `ContentBlock[]` to a simplified `{ output, isError }` (text blocks for the MVP), and emits an observability event. The explicit abort check matters because `ctx.tools.execute()` *catches* thrown tool errors and converts them to `isError` results — without the check, an aborted sub-call would look like ordinary error data and the program would keep running instead of stopping. Sub-dispatch still flows through the `tools/execute` waterfall, so permission/sandbox/hook plugins apply to code-mode calls exactly as to native ones.
+1. Builds the SDK bindings. For each real tool, an async `invoke(callArgs)` that **checks `exec.signal?.aborted` (throwing if set) before and after** calling `ctx.tools.execute({ callId: <deterministic sub-id>, name, arguments: callArgs, agent: exec.agent, signal: exec.signal })`, then maps the resulting `ContentBlock[]` to a simplified `{ output, isError }` (text blocks for the MVP), and emits an observability event. The explicit abort check matters because `ctx.tools.execute()` *catches* thrown tool errors and converts them to `isError` results — without the check, an aborted sub-call would look like ordinary error data and the program would keep running instead of stopping. Sub-dispatch still flows through the `tools/pre-execute`/`tools/post-execute` waterfalls, so permission/sandbox/hook plugins apply to code-mode calls exactly as to native ones.
 2. Calls `ctx.codeRuntime.run({ code: args.code, sdk: bindings, signal: exec.signal })`.
 3. Surfaces the outcome. A *successful* run returns `[{ type: 'text', text: <console logs + return value> }]`. A *runtime-error* result cannot be reported by returning content, because a normal `ToolDefinition.execute()` returns only `Promise<ContentBlock[]>` and `ToolRegistry.execute()` hardcodes `isError: false` on any successful return — `isError: true` arises only from the registry's catch path. So on an error result the tool **throws a `CodeRunError extends HarnessError`** (`HarnessError` is exported from `dsh-llm`; the registry catch turns any throw into `isError: true` with the message as text, and a `HarnessError` additionally carries structured `{ name, code }`). An alternative — registering `run_code` handling as a `tools/execute` listener that returns a full `ToolExecutionResult` and can set `isError` directly — is noted; the throw is simpler and preferred.
 

docs/rfc/proposed/feature/2026-06-30-pre-tool-input-rewrite.md

@@ -0,0 +1,39 @@
+# RFC: Pre-tool input rewrite — a consistent design (proposed)
+
+Status: proposed (2026-06-30)
+
+<!-- XXX: legacy ADR/RFC body format, not yet normalized to a unified RFC template. -->
+
+## Context
+
+The [interception-seams RFC](../../implemented/feature/2026-06-30-interception-seams.md) added `tools/pre-execute` returning a `PreToolDecision` (allow/deny/ask) — but deliberately NOT input rewrite (a hook changing a tool call's `arguments` before it runs). Claude Code's `PreToolUse` hook offers an `updatedInput`, so a faithful CC bridge wants the same. This RFC designs that, separately, because doing it consistently is a real problem — not a field to bolt onto the allow decision.
+
+## The problem: three readers of pre-execution arguments
+
+In the loop, a tool call's arguments are committed to the log and read by live consumers BEFORE the tool executes:
+
+1. **`assistant/message`** is appended before tool dispatch — it is the model-history source `deriveMessages()` replays, so it carries the tool-call arguments the model itself emitted.
+2. **`tool/call`** is the durable AUDIT record, appended before `ctx.tools.execute()`.
+3. **Live presentation reads `tool/call.arguments`**: the ACP bridge remembers them and passes them to `presentResult`; `dsh-tool-bash` derives the card title, the rawInput, the cwd, and the terminal-vs-background treatment from them.
+
+So an "input rewrite" that changes ONLY what executes would make the UI show one command while another RAN, and render result state against the wrong arguments — a real inconsistency, not a documentable gap. (The existing low-level capability to mutate `exec.arguments` in a listener has exactly this latent inconsistency; it is unadvertised precisely because of this.)
+
+## Proposed design (sketch — to validate against the code when built)
+
+Treat input rewrite as a consistency unit: when a `pre-execute` hook supplies `updatedInput`, the rewrite must be reflected in ALL three readers, atomically, before execution:
+
+- The `tool/call` audit event records the REWRITTEN arguments (with the original retained in a sidecar field for the audit trail — a hook changed the call, and both the original and the effective arguments are facts worth keeping).
+- The `assistant/message` in derived history must agree with what executed — options to evaluate: rewrite the assistant message's tool-call block in place (changes what the model "sees it said"), or record a separate correction the next request carries. The CC model is that the model sees the rewrite took effect.
+- Presentation (`presentCall`/`presentResult`) reads the rewritten arguments, so the UI shows what actually ran.
+
+The shape would extend `PreToolDecision` with an allow-variant `arguments` (or a dedicated `{kind:'rewrite', arguments}`), and the loop would thread the rewrite through the three readers above rather than only into `ctx.tools.execute()`.
+
+## Why not now
+
+The interception-seams RFC notes input rewrite "fought the code across two review rounds" — the signal AGENTS.md names for an over-reaching change. Shipping allow/deny/ask first keeps the seam honest (no advertised contract that silently desyncs the UI), and a CC/Codex bridge that receives an `updatedInput` logs it and surfaces a faithful-but-degraded warning (like `ask`→deny) until this lands. This RFC is the home for the consistent design; `TODO(pre-tool-input-rewrite)` in the loop's pre-execute call site anchors it.
+
+## Open questions
+
+- Does rewriting the `assistant/message` tool-call block corrupt any provider's expectation on replay, or is a separate correction safer?
+- Should the original arguments be preserved on the `tool/call` event (audit) and, if so, under what field?
+- How does this interact with a future permission `ask` flow (a user approving a rewritten call)?

docs/rfc/proposed/simplification/2026-06-20-remove-agent-boundary-mirror-events.md

@@ -1,31 +0,0 @@
-# RFC: Stop mirroring durable boundaries as agent events
-
-Status: proposed
-
-## Problem
-
-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`.
-
-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.
-
-## Proposal
-
-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.
-
-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.
-
-## Acceptance criteria
-
-- ACP and stdio render transcript content from `session/event`.
-- `agent/turn-start`, `agent/turn-end`, `agent/step-start`, `agent/step-end`, and `agent/steering` are removed or reduced to private implementation details.
-- `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.
-- Tests assert the persisted event stream, not a second mirror stream, for turn and step ordering.
-- Documentation presents `SessionEvent` as both the durable source and the live transcript feed.
-
-## What we give up
-
-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.
-
-## Related
-
-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.