feat(modes): per-session sandbox/approval switching — the session log as the store, ACP config options

effective(session) = findLast(the session own knob events)?.value ?? the
composition-config default. One log-only event per knob, owned by its
domain (bash/sandbox-mode in dsh-bash, approval/policy in dsh-approval),
each exporting the same three-piece kit: the event declaration, a pure
fold, and THE write path — a switch IS its event; no owner service, no
facts map. Restart immunity and multi-session isolation fall out of the
log replay by construction.

Execution follows the fold on both sides: the bash tool stamps
escalation grant > session override > executor default, and the approval
seam prepends the never-gate that auto-rejects before any interactive
answerer. Visibility is two layers per knob: a per-agent prompt section
states the effective value on every request (logged through
request/header*, so what-the-model-was-told replays from the log), and an
agent/pre-step narrator injects at most one coalesced delta notice with
positional attribution (user switch vs operator/config drift). The ACP
bridge advertises one capability-gated select per composable knob with
currentValue folded per session, validates set_config_option against the
closed vocabularies, and anchors idle switches at the next turn
prompt-submit under the turn-enclosure contract.

docs/config-catalog.md

@@ -31,7 +31,7 @@ export interface AcpConfig {
 
 Depends on: `Stream` (`@agentclientprotocol/sdk`)
 
-Source: [`packages/ui/acp/src/index.ts:241`](../packages/ui/acp/src/index.ts)
+Source: [`packages/ui/acp/src/index.ts:248`](../packages/ui/acp/src/index.ts)
 
 ## `@deepseek-ai/dsh-acp-agent`
 
@@ -130,6 +130,37 @@ Depends on: [`AgentId`](../packages/core/agent/src/index.ts) · [`AgentOptions`]
 
 Source: [`packages/core/agent-loop/src/index.ts:36`](../packages/core/agent-loop/src/index.ts)
 
+## `@deepseek-ai/dsh-approval`
+
+```ts config-catalog
+/** Plugin config. All optional — `static Config` supplies the defaults. */
+export interface Config {
+  /**
+   * The deployment's default {@link ApprovalPolicy} for sessions without an
+   * `approval/policy` override — `'ask'` delegates to the composed answerers
+   * (fail-closed with none); `'never'` auto-rejects every ask without
+   * prompting (the deterministic CI/unattended stance).
+   */
+  policy?: ApprovalPolicy
+}
+
+/**
+ * A session's approval policy — what happens to an {@link ApprovalService}
+ * ask BEFORE any interactive answerer sees it:
+ *
+ * - `'ask'` (the default) — delegate to the composed answerers; with none
+ *   composed the chain falls through to the fail-closed `'unavailable'`
+ *   (exactly today's behavior).
+ * - `'never'` — never prompt anyone: every ask resolves `'rejected'`
+ *   deterministically. The strict headless stance (CI, unattended runs) and
+ *   the only policy value stated in the system prompt — unlike `'ask'`, its
+ *   outcome is knowable without asking, so stating it cannot overclaim.
+ */
+export type ApprovalPolicy = 'ask' | 'never'
+```
+
+Source: [`packages/approval/approval/src/index.ts:244`](../packages/approval/approval/src/index.ts)
+
 ## `@deepseek-ai/dsh-bash-local`
 
 ```ts config-catalog
@@ -1029,7 +1060,6 @@ Source: [`packages/workflow/workflow-workerthread/src/index.ts:69`](../packages/
 These load from a `cordis.yml` entry with no `config:` block; they declare no config surface.
 
 - `@deepseek-ai/dsh-agent` ([`packages/core/agent/src/index.ts`](../packages/core/agent/src/index.ts))
-- `@deepseek-ai/dsh-approval` ([`packages/approval/approval/src/index.ts`](../packages/approval/approval/src/index.ts))
 - `@deepseek-ai/dsh-fs-policy` ([`packages/fs/fs-policy/src/index.ts`](../packages/fs/fs-policy/src/index.ts))
 - `@deepseek-ai/dsh-llm` ([`packages/llm/llm/src/index.ts`](../packages/llm/llm/src/index.ts))
 - `@deepseek-ai/dsh-session` ([`packages/core/session/src/index.ts`](../packages/core/session/src/index.ts))