deepseek-harness/packages/hooks/hooks-codex/README.md

@deepseek-ai/dsh-hooks-codex

A cordis plugin that runs a user's existing Codex hooks.json on the harness's canonical interception seams. The Codex dialect half of the hooks subsystem. The dialect-agnostic primitives come from @deepseek-ai/dsh-hook-protocol; this bridge owns the Codex-specific payloads, matcher mode, and decision mapping.

Codex's hook protocol is a deliberate subset of Claude Code's (same hooks.json shape):

• Five hook points only: PreToolUse, PostToolUse, SessionStart, UserPromptSubmit, Stop — no subagent / notification / compaction hooks.
• Regex-only matchers (no literal fast path; the matcher is always an unanchored regex).
• snake_case stdin payloads with turn_id/model extras, written without a trailing newline.
• No env vars and no command substitution (a literal ${…} in a command survives verbatim).
• A block-only decision model — allow/ask are not honored; a hook can only block, never pre-approve.

A native cordis plugin could do everything this bridge does, more powerfully; the bridge exists only to run UNMODIFIED external Codex hooks faithfully (see the interception-seams RFC).

Config

import type { Config } from '@deepseek-ai/dsh-hooks-codex'
const config: Config = {
  configPath: '/path/to/.codex/hooks.json', // required
  model: 'deepseek-v4',                      // optional: stamped on every payload (Codex includes `model`)
  defaultTimeoutMs: 600_000,                 // optional: per-hook timeout when a hook sets none
  stderrSummaryMaxChars: 500,                // optional: char cap on the hook/result event's persisted stderr summary
}

In a cordis.yml:

- dsh-hooks-codex:
    configPath: ./.codex/hooks.json
    model: deepseek-v4

The config is parsed once at load. configPath is process-level — a relative path resolves against the process launch cwd at load time, not per-session (TODO(per-session-hook-config)). A read/parse failure is contained (logs + registers nothing). Only sync type: 'command' hooks run — a non-command or async: true hook is parsed-and-skipped with a warning. A hook accepts timeout or the timeoutSec alias; one that sets neither runs under the protocol's reference default (DEFAULT_HOOK_TIMEOUT_MS from dsh-hook-protocol, 10 minutes). Events outside the five Codex points are dropped at parse.

The hooks themselves run in the agent's session workspace: for the agent-scoped points the bridge passes the session's cwd as the hook process's working directory, so a hook operates in the user's project tree, not the server launch dir.

Hook points → seam Decisions

Codex hook	Harness seam	Mapping
SessionStart	agent/session-start (emit)	a plain-stdout hook's output → additionalContext → agent.inject()
UserPromptSubmit	agent/prompt-submit (waterfall)	block (exit 2) → PromptDecision.block; additionalContext-only → delegate via next() then fold context onto the downstream decision
PreToolUse	tools/pre-execute (waterfall)	block → PreToolDecision.deny (no allow/ask)
PostToolUse	tools/post-execute (waterfall)	block → block with feedback; additionalContext-only → delegate via next() then fold context onto the downstream decision (a Code Mode sub-call’s context is dropped by the run_code bridge — see the pipeline doc)
Stop	agent/turn-continuation (waterfall)	a blocking Stop hook forces continue with the reason as next-step steering

A tool call's payload carries the real tool_name (the same value the matcher tests) and Codex's tool_input: { command } shape (the command arg when present, else ''). The matcher subject is the tool name (PreToolUse/PostToolUse) or the session source (SessionStart); UserPromptSubmit/Stop ignore matchers.

SessionStart — the one emit point — runs detached; each run chain is tracked, and disposing the bridge aborts a still-running hook process, then drains the continuation before the dispose resolves (createDetachedRuns in dsh-hook-protocol).

Context source

Injected context carries an explicit { kind: 'plugin', plugin: 'hooks-codex' } source (agent.inject() would otherwise default it to { kind: 'user' }).

Known Limitations and Deferred Work

• Stop loop-guard (TODO(stop-loop-guard)) — as in CC, a Stop hook that unconditionally blocks would force-continue every step (stop_hook_active is always false here); the loop-guard is deferred, and a hook author must self-limit until it lands.
• systemMessage — a hook's user-facing warning is logged + warned, not surfaced; there is no user-message channel on these seams yet (only model-facing additionalContext).
• {"continue": false} is recorded, not enforced — the hook/result event records decision stop, but the run is not halted (TODO(hook-continue-false)).
• SessionStart cannot gate the first turn — agent/session-start is a synchronous emit with a detached continuation, so a hook's injected context lands best-effort before turn 1 (TODO(session-start-gating)).
• Hook config is process-level — one configPath parsed at load for the whole process; per-session discovery of a project-local config is deferred (TODO(per-session-hook-config)).