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%.
Tianyi Cui