feat(timeout): add tools/execute seam + tool-timeout policy plugin

Model-facing tool-call budgets were tangled into each capability's schema
(bash timeoutMs, web_fetch timeout_ms) with no shared home. Add a
tools/execute around-dispatch waterfall to dsh-tools whose base next() is
the dispatch-with-normalization thunk, and a new @deepseek-ai/dsh-timeout-policy
plugin (packages/timeout/) that arms a per-tool deadline on exec.signal and
returns a structured TOOL_TIMEOUT when it wins. Migrate web_fetch (drop the
model-facing timeout_ms) and web_search onto it; the fetch provider keeps its
timeout only as a resource backstop for direct callers. bash and hook command
execution keep BASH_TIMEOUT unchanged.

Named the plugin timeout-policy (not the RFC's tool-timeout) so it does not
trip the gen-tool-catalog packages/*/tool-* completeness guard, and replace
exec.signal by in-place mutation before next() since cordis waterfall next()
ignores passed arguments. RFC moved to implemented/ recording both deviations.

docs/cordis-catalog/events.md

@@ -307,11 +307,23 @@ A tool was registered or unregistered (the available tool set changed).
 'tools/change'(): void
 ```
 
+Source: [`packages/core/tools/src/index.ts:108`](../../packages/core/tools/src/index.ts)
+
+### `tools/execute` — waterfall
+
+Around-dispatch waterfall wrapping the registry's core tool dispatch, between the `tools/pre-execute` gate and the `tools/post-execute` seam. A listener receives `(exec, next)`: call `next()` to delegate to dispatch (returning its ToolExecutionResult, optionally wrapped), or return a replacement result without calling `next()` to short-circuit dispatch. The base `next()` IS the dispatch-with-normalization thunk — a thrown tool (or unknown tool) is already normalized to an `isError` result by the time a listener's `await next()` returns, so a wrapper never sees a raw throw from the tool body. This is the seam a timeout/retry/metrics plugin wraps: it can mutate `exec` (e.g. replace `exec.signal` with a per-call deadline) BEFORE `next()` and inspect the result AFTER. (Cordis `next()` ignores any passed arguments and re-invokes downstream with the shared payload, so a wrapper mutates `exec` in place rather than passing a new object to `next()`.) Multiple listeners compose by registration order — an outer one wraps the inner ones plus dispatch.
+
+```ts cordis-catalog
+'tools/execute'(this: ToolRegistry, exec: ToolExecution, next: () => Promise<ToolExecutionResult>): Promise<ToolExecutionResult>
+```
+
+Types: [ToolExecution](../core-data-structures/tools.md) · [ToolExecutionResult](../core-data-structures/tools.md)
+
 Source: [`packages/core/tools/src/index.ts:87`](../../packages/core/tools/src/index.ts)
 
 ### `tools/post-execute` — waterfall
 
-Waterfall AFTER a tool runs — where hook plugins inspect the result and accept it (optionally REPLACING the model-facing content, and/or attaching `additionalContext` for the next request) or block it with corrective `feedback` (Claude Code's `PostToolUse`). Listeners receive `(exec, result, next)`: call `next()` to delegate to the default (accept unchanged), or return a PostToolDecision to override. The core tool dispatch sits between the two waterfalls as plain code, all inside `execute`'s outer try/catch (and the tool body keeps its own inner try/catch, so a thrown tool still reaches `post-execute` as an `isError` result).
+Waterfall AFTER a tool runs — where hook plugins inspect the result and accept it (optionally REPLACING the model-facing content, and/or attaching `additionalContext` for the next request) or block it with corrective `feedback` (Claude Code's `PostToolUse`). Listeners receive `(exec, result, next)`: call `next()` to delegate to the default (accept unchanged), or return a PostToolDecision to override. Core tool dispatch runs earlier as the base `next()` of the `tools/execute` waterfall, all inside `execute`'s outer try/catch (and the tool body keeps its own inner try/catch, so a thrown tool still reaches `post-execute` as an `isError` result).
 
 ```ts cordis-catalog
 'tools/post-execute'(this: ToolRegistry, exec: ToolExecution, result: ToolExecutionResult, next: () => Promise<PostToolDecision>): Promise<PostToolDecision>
@@ -319,7 +331,7 @@ Waterfall AFTER a tool runs — where hook plugins inspect the result and accept
 
 Types: [ToolExecution](../core-data-structures/tools.md) · [ToolExecutionResult](../core-data-structures/tools.md)
 
-Source: [`packages/core/tools/src/index.ts:82`](../../packages/core/tools/src/index.ts)
+Source: [`packages/core/tools/src/index.ts:103`](../../packages/core/tools/src/index.ts)
 
 ### `tools/pre-execute` — waterfall
 
@@ -331,7 +343,7 @@ Waterfall BEFORE a tool runs — the gate where sandbox, permission, and hook pl
 
 Types: [ToolExecution](../core-data-structures/tools.md)
 
-Source: [`packages/core/tools/src/index.ts:66`](../../packages/core/tools/src/index.ts)
+Source: [`packages/core/tools/src/index.ts:67`](../../packages/core/tools/src/index.ts)
 
 ## Inherited events (cordis core + loader/hmr/timer)
 

docs/cordis-catalog/services.md

@@ -193,7 +193,7 @@ Source: [`packages/core/system-prompt/src/index.ts:198`](../../packages/core/sys
 
 ## `ctx.tools` — `ToolRegistry`
 
-Tool registry (`ctx.tools`): tool plugins register definitions; the agent loop executes calls through the `tools/pre-execute` → dispatch → `tools/post-execute` pipeline. The registry contributes its schemas into the system-prompt assembly.
+Tool registry (`ctx.tools`): tool plugins register definitions; the agent loop executes calls through the `tools/pre-execute` → `tools/execute` → `tools/post-execute` pipeline. The registry contributes its schemas into the system-prompt assembly.
 
 ```ts cordis-catalog
 register(definition: ToolDefinition): () => void
@@ -204,7 +204,7 @@ async execute(exec: ToolExecution): Promise<ToolExecutionResult>
 
 Types: [ToolDefinition](../core-data-structures/tools.md) · [ToolExecution](../core-data-structures/tools.md) · [ToolExecutionResult](../core-data-structures/tools.md)
 
-Source: [`packages/core/tools/src/index.ts:268`](../../packages/core/tools/src/index.ts)
+Source: [`packages/core/tools/src/index.ts:289`](../../packages/core/tools/src/index.ts)
 
 ## `ctx.web` — `WebService`