Address review on the bridges:
- Hook cwd (blocking): the bridges never passed a workdir to runHook, so hooks
ran in the executor default (the ACP server launch dir), not the session
cwd — a hook doing `pwd`/relative reads/marker writes operated in the wrong
tree. Both bridges now thread the agent's session `header.cwd` (the
session/new.cwd) as the hook workdir for agent-scoped points. Regression per
bridge: server cwd ≠ session cwd, a `pwd` hook proves it ran in the session
workspace (proven red without the workdir).
- Example config honesty (blocking): `configPath: ./hooks.json` is read ONCE at
load against the PROCESS cwd, not per-session — the comment/README now say so
explicitly (a project-local per-session hooks.json is not discovered;
TODO(per-session-hook-config)). The hooks-run-in-session-cwd fix above is the
distinct, separately-documented half.
- Session-start timing (blocking): agent/session-start is a synchronous emit and
the hook runs on a detached .then, so injected context is BEST-EFFORT — not
guaranteed before the first request. Downgrade the contract in code comments +
README + RFC (TODO(session-start-gating)) rather than implying "first request
sees it", and add a no-wait regression that asserts the safe properties
without pre-waiting for the inject.
- systemMessage (non-blocking): the merge collects merged.systemMessages but no
bridge surfaced it. Warn per hook (like updatedInput) and document it as
deferred in both READMEs + the RFC; tests assert the warn + non-surfacing.
Review noted the module docs promised an invalid regex is "logged by the bridge",
but matchesMatcher only returns `false` — callers cannot distinguish a genuine
non-match from a compile failure, so a typo'd pattern silently disables that
matcher with no warning. Both bridges call matchesMatcher directly, so no log
happens anywhere. Correct the docs to state the silence explicitly; surfacing bad
config would need a diagnostic-returning variant or parse-time validation, marked
TODO(matcher-diagnostics). No behavior change.
Review noted the deep-clone of the child output runs inside `onFulfilled`,
OUTSIDE emitLifecycle's per-listener containment, and the settle `.then` is
`void`ed — so an uncloneable output (a future non-serializable content-block
type, or a contract-violating result) would throw and become an UNHANDLED
rejection, contradicting the "any throw is contained" guarantee the comment
claims. Wrap the clone in try/catch: on failure, log via ctx.logger.warn and
emit subagent/end WITHOUT lastAssistantMessage (preserving stopReason/agentType)
rather than dropping the event or crashing. Regression proves the unfixed code
produces an unhandled rejection.
- core-data-structures/core.md: the `agent/*` taxonomy said "turn/step
boundaries", but the step-boundary mirror emits were dropped — `agent/*`
mirrors only turn boundaries; step boundaries are durable `step/start`/
`step/end` session events. Narrow the catalog so plugin authors aren't pointed
at nonexistent `agent/*` step events.
- interception-seams RFC: replace stack-position phrasing ("a later stack PR",
"the stack's first change", "the PR that makes...") with durable mechanism/RFC
names (the hook bridge packages, the event-domain-semantics RFC).
- tools/post-execute snapshot: `dispatched.content` was the same array reference
as `result.content`, so a listener's in-place `push`/`splice` leaked into the
returned content while a reassignment was masked — the "protect from tampering"
comment over-claimed. Copy content into a fresh array so the snapshot guards
the array structure; comment now states it is not deep immutability. Regression
extended to push a block in-place and assert it does not leak (proven red
without the copy).
Review noted the handler's comment said "EPIPE" while the code swallowed every
stdin 'error'. Swallowing any stdin-write error IS correct here — the write is
best-effort and the command's authoritative outcome is its exit code + captured
output (reported by the `close` handler regardless of whether the write landed).
A rare non-EPIPE pipe fault means the command ran with incomplete stdin, which
it surfaces itself via its own exit/output; rejecting `done` would instead
discard that real output and turn it into an opaque infrastructure error. Widen
the comment to state this rather than implying only EPIPE is caught. No behavior
change.
Round-2 Codex review of the round-1 fixes:
- (A) The Codex plain-stdout→additionalContext fold (F1) was not gated on exit
code, so a NON-clean hook's stdout still injected: a SessionStart `echo stale;
exit 2` (an emit — cannot block) wrongly injected "stale", and a
UserPromptSubmit `exit 1` (non-blocking error → falls through to context) did
too. Gate the fold on `output.exitCode === 0`, matching the codec's own
structured-stdout rule. Guard tests for both paths, proven red without the gate.
- (B) The Codex "SessionStart no-context no-op" absence test was unsound (a
completed turn doesn't prove the detached hook finished). It now touches a
marker and waitFor()s it before asserting no context.
- (B) Both HMR tests used a no-op `true` hook, so a leaked listener would still
pass. They now use a BLOCKING (exit 2) UserPromptSubmit hook and assert the
post-dispose turn is NOT blocked and logs no hook/invoked — a leaked listener
fails loudly.
The bridge tests that drive observe-only emit listeners (session-start,
subagent/start, subagent/end) fire their hook on a detached `.then` the test
cannot await. They waited a fixed 50-80ms, which flaked under the full
test:coverage run's heavy parallel load (transform ~400s): the sleep expired
before the async hook completed, so the injected context / marker file / warn
call had not landed. Replace each fixed sleep with a `waitFor(predicate)` poll
that retries until the observable effect appears (5s deadline) — "async state is
not synchronous state": wait for the signal that actually fires, not a guessed
duration. No behavior change; the same assertions, made robust to scheduling.
Wire the bridges to the codec's new discriminator check (merged down from
dsh-hook-protocol): each bridge passes its firing `point` as `expectedEventName`
to runHook, so a hook whose `hookSpecificOutput.hookEventName` names a different
event has its event-scoped fields discarded. Bridge-level guard test: a
PreToolUse hook emitting a UserPromptSubmit-labeled deny no longer denies the
tool (proven red without the wiring, then reverted).
Round-1 Codex review findings on the bridges:
- Stop force-continue (both bridges): a blocking Stop hook with EMPTY stderr
yielded decision 'deny' + reason undefined, and the `&& reason !== undefined`
guard let the turn STOP — the opposite of a blocking Stop hook. Force-continue
on any deny; fall back to a generic steering line when there is no reason.
- Codex payload tool_name: hardcoded "Bash" disagreed with the exec.name matcher
subject, so a real Codex `matcher:"Bash"` never fired against the harness's
lowercase `bash` tool. Use exec.name in both payload builders (matches the
matcher subject and the sibling CC bridge). Doc/RFC updated.
- Codex plain-stdout context: SessionStart/UserPromptSubmit are documented to
treat a clean hook's PLAIN (non-JSON) stdout as additionalContext, but nothing
folded it. runPoint now folds plain stdout into context for those two events,
gated on the codec's JSON gate so structured stdout is never dumped as prose.
- continue:false is deferred, not honored: the seams have no hard-halt primitive
yet. TODO(hook-continue-false) at both bridges + an RFC deferred note; the two
tests now assert the LOG records the halt request AND that the run is NOT
actually halted (no longer misleading).
- README concurrency wording: hooks run SERIALLY (deliberate — adjacent
invoked/result log pairs, order-independent fold), not concurrently. Fixed the
CC README claim + an RFC note.
Regression guards proven red on the unfixed code, then reverted. The mismatched-
hookEventName discard (also flagged) is fixed in dsh-hook-protocol and merged down.
The reference schemas key the `hookSpecificOutput` block by `hookEventName`, so
a block naming a DIFFERENT event than the one firing is malformed — a hook
emitting `hookSpecificOutput.hookEventName: "PreToolUse"` on a `Stop` event must
not deny the Stop. The codec surfaced `hookEventName` for a bridge to compare but
never enforced the discard, so both bridges pushed every parsed output into the
merge unconditionally.
parseHookOutput now takes an optional `expectedEventName`; when the block's
`hookEventName` names a different event, its event-scoped fields
(permissionDecision/permissionDecisionReason/additionalContext/updatedInput) are
discarded (the discriminator is still surfaced for the log, and the
event-agnostic top-level decision/continue/etc. are unaffected). runHook threads
it via RunHookOptions.expectedEventName; a caller that omits it opts out.
Codex review finding on the bridges PR (PR-F); fixed here on the codec that owns
the fold and knows field provenance, then flows down to both bridges.
The two bridge plugins that run a user's existing Claude Code / Codex hook
config on the harness's typed interception seams, built on the shared
dsh-hook-protocol library. A bridge is a faithfulness adapter, not a power
tool: anything it does a native cordis plugin does more powerfully — the
bridge exists only to run UNMODIFIED external hooks.
- dsh-hooks-claude: CC dialect. Seven hook points (SessionStart,
UserPromptSubmit, PreToolUse, PostToolUse, Stop, SubagentStart,
SubagentStop), CC per-event stdin payloads, env + ${CLAUDE_PLUGIN_ROOT}/
${CLAUDE_PROJECT_DIR} substitution, literal-or-regex matcher.
- dsh-hooks-codex: Codex dialect — a deliberate subset. Five hook points,
always-regex matcher, snake_case payloads (turn_id/model, no trailing
newline), no env/substitution, block-only decisions.
Both map the neutral merged outcome onto the seam's typed Decision and stamp
an explicit {kind:'plugin'} source on injected context (so it is never
mislabeled as a user prompt). Config parse-failure is contained; only command
hooks run. updatedInput is logged+warned (input rewrite deferred); the Stop
loop-guard is deferred (TODO).
Tests: per-file 100% — config-parse unit branches + per-seam mappings
end-to-end through the REAL loop + REAL bash + REAL shell scripts (scripted
mock model only) + a real-Loader export-shape guard. A keyless ACP snapshot
scenario (hook-prompt-block) proves a UserPromptSubmit hook blocks a prompt
end-to-end (rejected turn -> ACP cancelled, hook/* events in the log); a
with-key e2e (hooks.e2e.ts) proves a PreToolUse hook blocks real bash
(verified on disk). The snapshot normalizer now scrubs hook/result.durationMs.
RFC: docs/rfc/implemented/feature/2026-06-30-hook-bridges.md
mergeHookOutputs collected reasons only from rank-3 (deny/block) hooks, so an
ask-winning outcome lost its reason — a bridge mapping an `ask` decision to a
PreToolDecision had no reason to attach. Collect reasons per rank and emit the
ones explaining the winning decision: a deny-winning fold shows deny reasons, an
ask-winning fold shows ask reasons, allow contributes none. Found while building
the hooks-claude bridge's PreToolUse `ask` path.
Codex's PR-E review found three protocol-fidelity blockers + two doc gaps, all
verified against ~/repos/refs:
- (A) Top-level `decision` accepted allow/deny/ask, but both reference schemas
reserve those for hookSpecificOutput.permissionDecision — the legacy top-level
decision is approve/block ONLY. Split topLevelDecisionOf (approve/block) from
permissionDecisionOf (allow/deny/ask), so an out-of-band {"decision":"deny"} is
now invalid and ignored instead of becoming a real blocking decision.
- (A) hookSpecificOutput was parsed without its hookEventName discriminator.
HookOutput now surfaces hookEventName so a bridge can discard a block whose
claimed event doesn't match the firing one (the schemas key the block by event).
- (A) runHook discarded raw stdout. HookOutput now carries `stdout` (trimmed,
verbatim) so a bridge can reproduce CC's plain-stdout rendering / Codex's
plain-stdout-as-additionalContext behavior.
- (B) hook/* SessionEventMap variants were only named in prose; added a payload/role
table to core-data-structures/session.md (a maintained catalog surface).
- (B) Removed PR-stack-position references (PR-F / "future bridge packages") from a
test comment and the RFC, per the current-state-wording rule.
New codec tests: top-level allow/deny/ask invalid+ignored, hookEventName capture,
raw stdout preserved on plain + JSON + empty stdout. 51 tests, per-file 100%.
Codex review caught an observe-only violation: the subagent/end emit fires from a
detached `.then` registered BEFORE start() returns — so before the caller's own
`await run.result` continuation runs. Carrying `result.output` by reference let a
mutating subagent/end listener corrupt the SubagentResult.output the caller/tool
then consumes. structuredClone() makes the event a read-only snapshot. Added a
regression test that mutates the event's array and asserts the caller's result is
untouched; proven to fail red without the clone. Updated the RFC + READMEs to note
the clone is load-bearing for the observe-only guarantee.
A hooks bridge translating SubagentStart/SubagentStop needs to know WHICH kind of
subagent ran and WHAT it produced — Claude Code's hooks carry subagent_type and the
child's final message. Enrich the existing lifecycle emits to match, observe-only:
- agentType: an optional caller-supplied subagent-kind label (CC's subagent_type),
added to SubagentStartRequest and carried VERBATIM onto both subagent/start
(SubagentRunInfo) and subagent/end (SubagentRunEndInfo). The seam never interprets
it. dsh-tool-subagent threads it from a new optional Config.agentType, so a
deployment exposing multiple subagent kinds (one tool load per kind) labels each.
- lastAssistantMessage: the child's final output (SubagentResult.output), added to
SubagentRunEndInfo on the settle path so an observer sees what the subagent
produced without holding the run. Absent on the reject path (no result produced).
Strictly observe-only: both events stay plain emits (subagent/end fires from a
detached .then and awaits no listener). A control-flow subagent/end (awaited
waterfall returning a decision) would need the emit→waterfall reshape, awaiting
listeners before settling, and a provider resume capability — deferred to the
background/steering redesign (FIXME(subagent-continuation) anchors it). RFC:
implemented/feature/2026-06-30-subagent-observe-enrich.md.
Codex's confirmation review confirmed blocker #1 (post-execute mutation) fixed and
the guard real, but found three current-state references the first sweep missed
(they phrase the seam without the literal "tools/execute" string):
- packages/core/tools/src/index.ts: the ToolExecution JSDoc said "flows through the
execution waterfall" → now names the pre-execute → dispatch → post-execute pipeline.
- packages/core/tools/src/schema.ts: ToolArgsError's JSDoc said "the registry's
execute waterfall catches it" → "the registry's execution pipeline".
- AGENTS.md repo layout still described tools/ as "tool registry + tools/execute
waterfall" → "tools/pre-execute/post-execute pipeline".
Doc-comment-only; no behavior change.
Codex's PR-C review found two (A) blockers:
- tools/post-execute could corrupt the protected outcome. postExecute passed the
mutable `result` to listeners and then read result.callId / spread result on the
return paths, so a listener mutating the reference (flipping isError, rewriting
callId, injecting an error) escaped the decision channel. Now the authoritative
callId/isError/error are SNAPSHOT before the waterfall and the return value is
rebuilt from the snapshot + the typed PostToolDecision — the decision is the only
sanctioned way to change the outcome, and callId is always exec.callId. Added a
regression test that mutates the result reference and asserts it has no effect;
proven to fail red on the unfixed code.
- Public docs/JSDoc still advertised the removed `tools/execute` waterfall after the
split. Swept every current-state reference to tools/pre-execute + tools/post-execute:
the ToolRegistry class JSDoc (and the regenerated catalog), loop.ts's ASCII flow
(also added the prompt-submit/session-start steps it was missing), the package-map
READMEs (packages, core, agent-core), core-data-structures core.md/tools.md, the
bash + acp + invariants src/READMEs (the deferred permission gate is the
tools/pre-execute deny/ask seam now), the cookbook, and the implemented RFCs whose
factual seam catalog drifted. codec.ts's totality prose now lists `rejected`.
Proposed-RFC references are left as-is (frozen proposals, validated when built).
Reshape the agent's interception surface so every seam returns a small, typed
Decision union, and the set covers the hook points a CC/Codex bridge (and a
native plugin) needs. "Native hooks" are not a package — a native hook is just a
cordis plugin on these canonical events; the bridges (a later PR) only translate
an external protocol onto the same surface.
dsh-agent:
- NEW agent/session-start(agent, source) emit (once before turn 1; SessionStartSource
startup|resume|clear|compact) — a pure notification, seeds context via inject().
- NEW agent/prompt-submit waterfall → PromptDecision (allow, optionally rewriting the
prompt or attaching additionalContext, or block).
- RESHAPE agent/turn-continuation boolean → ContinuationDecision ({action:'stop'} |
{action:'continue', reason?}; a continue reason is recorded as next-step steering).
- New HookContext envelope (required source — inject() would mislabel a missing one).
dsh-tools: split the single tools/execute waterfall into tools/pre-execute
(PreToolDecision allow/deny/ask gate) and tools/post-execute (PostToolDecision
accept/block, optionally replacing content or attaching additionalContext). Core
dispatch sits between as plain code; the tool body keeps its inner try/catch so a
thrown tool still reaches post-execute as an isError. ToolExecutionResult gains
additionalContext (ferried to the loop's per-step buffer). Input rewrite is
deliberately NOT offered (a proposed RFC designs it consistently).
dsh-session: new `rejected` TurnEndReason — a turn whose whole prompt batch was
blocked by prompt-submit.
agent-loop firing points: session-start emitted at create (source threaded —
startup for create/fork, resume for resume()); prompt-submit per drained message
with the always-open-turn rule (a fully-blocked batch is a zero-step rejected
turn); the continuation reshape; post-tool additionalContext buffered and appended
after all tool/results (adjacency). ACP codec maps rejected→cancelled.
A worked native-plugin example (interception.spec.ts) proves all four seams compose
end-to-end through the real loop with NO hook/* events (those belong to the bridge
lib). All existing tools/execute + turn-continuation tests migrated. The
tool-subagent abort test now aborts after a microtask so it still exercises the
live onAbort bridge (execute() awaits pre-execute before the body runs).
RFCs: implemented/feature/2026-06-30-interception-seams.md (the reshape) +
proposed/feature/2026-06-30-pre-tool-input-rewrite.md (the deferred rewrite design).
- The implemented RFC named stack positions (PR-A…PR-F, "the hooks bridges (PR-F)")
as shipped reality, violating the rule that an implemented RFC describes current
truth and docs never name a change unit the reader cannot see. Rephrased to
describe the hooks subsystem / a hook bridge as the standing motivating consumer,
without PR/stack references. The decision and rationale are unchanged.
- childEnv's comment pointed at dsh-tool-bash's "module doc" for the trusted-plugin
boundary, but that explanation lives in the package README (§ "Trusted-plugin
boundary"), not the module JSDoc. Fixed the reference.
The hooks subsystem runs external hook commands the Claude Code / Codex way:
JSON payload on stdin, context in CLAUDE_PROJECT_DIR / CLAUDE_PLUGIN_ROOT env.
Reusing the ctx.bash seam for that needs two new inputs — but stdin and arbitrary
env are exactly what dsh-bash-local's credential scrub exists to keep away from
model-driven commands. So this adds them as a TRUSTED-PLUGIN surface:
- BashExecRequest + BashExecSpec gain optional `stdin` and `env`. They are plain
optionals on the resolved spec (not required-but-nullable like `owner`): a
missing one means "none", the safe default, not a security footgun.
- dsh-bash-local threads them through resolve/run/start. `env` merges AFTER the
credential scrub, so a trusted caller's explicit entry wins even on a
credential-shaped name — the scrub guards the harness's OWN ambient creds from
model-driven commands, not a trusted plugin. stdin is always a pipe, closed
immediately (with bytes when supplied, empty otherwise — EOF as before); an
EPIPE from a child that exits without reading is swallowed.
- The model-facing dsh-tool-bash NEVER forwards model input into stdin/env (its
request is command/workdir/timeoutMs/signal/owner only). A regression guard
drives the real tool with adversarial args and asserts the request carries
neither field — proven to go red if the consumer ever forwards them.
Configurable scrub (in an earlier sketch) is dropped as speculative: the explicit
`env` field already gives a trusted caller full control, and no caller needs to
broaden the ambient scrub. Documented in a new architecture RFC, the bash.md
type-equiv blocks, and the three bash READMEs.
The continuation-override comment said "step-end/continuation listeners". With no
agent/step-end emit, the surviving step-boundary listener is the durable step/end
SESSION event, so spell it "step/end session-event/continuation listeners" to avoid
implying a removed agent/* mirror. Comment-only; no behavior change.
Second-round Codex review of the PR-A taxonomy change found four issues, all
verified against the code:
- The /goal regression guard asserted only that the steered content reached
requests[1], which passes even with the hasSteering override (loop.ts) disabled:
leftover steering is re-enqueued as a next-turn queued message and also lands in
requests[1], one turn later. The guard now asserts the same-turn shape — ONE
turn, TWO steps, a steering/message recorded before step 2 — which is the
mechanism the override drives. Proven to fail red with the override disabled.
- The event-domain-semantics RFC's consequence list still described the pre-fix
behavior (step marked open AFTER step/start, so no step/end owed). It now states
the shipped behavior: the loop marks the step open BEFORE the append, so a
throwing step/start listener gets a balancing step/end via closeStep().
- architecture.md's loop pseudocode said only continuation listeners force
continuation; step/end session-event listeners (the /goal pattern) do too.
- The agent/turn-end JSDoc listed a `rejected` TurnEndReason that does not exist on
this branch (it belongs to the later interception work). Removed it and
regenerated the cordis catalog; `interrupted` (a real variant) stays.
Codex review of PR-A found three blockers:
- A throwing step/start session-event listener left an unbalanced log
(turn/start → step/start → turn/end with no step/end), which the invariants
oracle rejects — masked because that rejection was itself contained as a
throwing turn/end listener. Fix the root cause in the loop: mark the step open
BEFORE appending step/start (Session.append pushes before notifying), so the
outer catch's closeStep() appends the balancing step/end. The test now asserts
the balanced outcome (stepEnd:1, step/end before turn/end); proven load-bearing
(revert the reorder → the test goes red with stepEnd:0).
- Reintroduce the /goal-pattern guard deleted in the prior commit, migrated to a
step/end session-event listener (the surviving step-boundary hook point), with
a no-tools first step so it exercises the hasSteering continuation override.
- Update packages/core/agent/README.md: step boundaries are no longer agent/*
emits.
Pin the three-domain rule (session = durable fact log, agent = live runtime
surface, tools = registry/exec): a durable replayable fact is a SessionEvent; a
live interception or transient/live-object signal is an agent/tools Cordis
event. A boundary that is both is mirrored as an agent/* emit ONLY where a live
consumer needs the Agent handle.
Apply it to the boundary twins: drop agent/step-start and agent/step-end (no
production consumer needs the live Agent at a step boundary — consumers read the
durable step/start/step/end session events). Keep agent/turn-start/turn-end (the
stdio UI labels output by agent.id). Tests that observed step boundaries via the
removed emits now observe the durable session events; the pinned behavior is
unchanged.
Conservative subset of the proposed "remove boundary mirror events"
simplification; foundation for the Hooks subsystem's canonical event surface.
Yichen Jiang
Tianyi Cui
Ziya
kingwl
Hypatia May