Single /codex-runtime invocation could spawn 'codex --version' up to 3
times (state report, enable gate, success message). Each spawn is ~50ms,
so the cumulative cost wasn't a crisis, but it was wasteful and turned a
trivial slash command into something noticeably laggy on slower systems.
Refactored to lazy-once via a closure over a nonlocal cache. First call
spawns; subsequent calls in the same apply() reuse the result.
Behavior unchanged — same return shape, same error handling, same install
hint when codex is missing. Just one subprocess per call instead of three.
Two regression-guard tests added:
- test_binary_check_cached_within_apply: enable path → call_count == 1
- test_binary_check_cached_on_read_only_call: state-report path → call_count == 1
Total tests for /codex-runtime now 30 (was 28); all 143 codex-runtime
tests still green.
Translates the user's mcp_servers config from ~/.hermes/config.yaml into
the TOML format codex's MCP client expects. Wired into the
/codex-runtime codex_app_server enable path so users get their MCP tool
surface in the spawned subprocess automatically.
The migration runs on every enable. Failures are non-fatal — the runtime
change still proceeds and the user gets a warning so they can fix the
codex config manually.
What translates (mapping verified against codex-rs/core/src/config/edit.rs):
Hermes mcp_servers.<n>.command/args/env → codex stdio transport
Hermes mcp_servers.<n>.url/headers → codex streamable_http transport
Hermes mcp_servers.<n>.timeout → codex tool_timeout_sec
Hermes mcp_servers.<n>.connect_timeout → codex startup_timeout_sec
Hermes mcp_servers.<n>.cwd → codex stdio cwd
Hermes mcp_servers.<n>.enabled: false → codex enabled = false
What does NOT translate (warned + skipped per server):
Hermes-specific keys (sampling, etc.) — codex's MCP client has no
equivalent. Listed in the per-server skipped[] field of the report.
What's NOT migrated (intentional):
AGENTS.md — codex respects this file natively in its cwd. Hermes' own
AGENTS.md (project-level) is already in the worktree, so codex picks
it up without translation. No code needed.
Idempotency design:
All managed content lives between a 'managed by hermes-agent' marker
and the next non-mcp_servers section header. _strip_existing_managed_block
removes the prior managed region cleanly, preserving any user-added
codex config (model, providers.openai, sandbox profiles, etc.) above
or below.
Files added:
hermes_cli/codex_runtime_plugin_migration.py — pure-Python migration
helper. Public API: migrate(hermes_config, codex_home=None,
dry_run=False) returns MigrationReport with .migrated/.errors/
.skipped_keys_per_server. No external TOML dependency — minimal
formatter handles strings/numbers/booleans/lists/inline-tables.
tests/hermes_cli/test_codex_runtime_plugin_migration.py — 39 tests
covering:
- per-server translation (12): stdio/http/sse, cwd, timeouts,
enabled flag, command+url precedence, sampling drop, unknown keys
- TOML formatter (8): types, escaping, inline tables, error case
- existing-block stripping (4): no marker, alone, with user content
above, with user content below
- end-to-end migrate() (8): empty, dry-run, round-trip, idempotent
re-run, preserves user config, error reporting, invalid input,
summary formatting
Files changed:
hermes_cli/codex_runtime_switch.py — apply() now calls migrate() in
the codex_app_server enable branch. Migration failure logs a warning
in the result message but does NOT fail the runtime change. Disable
path (auto) explicitly skips migration.
tests/hermes_cli/test_codex_runtime_switch.py — 3 new tests:
test_enable_triggers_mcp_migration, test_disable_does_not_trigger_migration,
test_migration_failure_does_not_block_enable.
All 325 feature tests green:
- tests/agent/transports/: 249 (incl. 67 new)
- tests/run_agent/test_codex_app_server_integration.py: 9
- tests/hermes_cli/test_codex_runtime_switch.py: 28 (3 new)
- tests/hermes_cli/test_codex_runtime_plugin_migration.py: 39 (new)
User-facing toggle for the optional codex app-server runtime. Follows the
'Adding a Slash Command (All Platforms)' pattern from AGENTS.md exactly:
single CommandDef in the central registry → CLI handler → gateway handler
→ running-agent guard → all surfaces (autocomplete, /help, Telegram menu,
Slack subcommands) update automatically.
Surface:
/codex-runtime — show current state + codex CLI status
/codex-runtime auto — Hermes default runtime
/codex-runtime codex_app_server — codex subprocess runtime
/codex-runtime on / off — synonyms
Files changed:
hermes_cli/codex_runtime_switch.py (new):
Pure-Python state machine shared by CLI and gateway. Parse args,
read/write model.openai_runtime in the config dict, gate enabling
behind a codex --version check (don't let users opt in to a runtime
they have no binary for; print npm install hint instead).
Returns a CodexRuntimeStatus dataclass that callers render however
suits their surface.
hermes_cli/commands.py:
Single CommandDef entry, no aliases (codex-runtime is its own thing).
cli.py:
Dispatch in process_command() + _handle_codex_runtime() handler that
delegates to the shared module and renders results via _cprint.
gateway/run.py:
Dispatch in _handle_message() + _handle_codex_runtime_command() that
returns a string (gateway sends as message). On a successful change
that requires a new session, _evict_cached_agent() forces the next
inbound message to construct a fresh AIAgent with the new api_mode —
avoids prompt-cache invalidation mid-session.
gateway/run.py running-agent guard:
/codex-runtime joins /model in the early-intercept block so a runtime
flip mid-turn can't split a turn across two transports.
Tests:
tests/hermes_cli/test_codex_runtime_switch.py — 25 tests covering the
state machine: arg parsing (10 cases incl. case-insensitive and
synonyms), reading current runtime (5 cases incl. malformed configs),
writing runtime (3 cases), apply() entry point covering read-only,
no-op, codex-missing-blocked, codex-present-success, disable-no-binary-check,
and persist-failure paths (8 cases). All green.
Adjacent test suites confirm no regressions:
- tests/hermes_cli/test_commands.py + test_codex_runtime_switch.py:
167/167 green
- tests/agent/transports/: 283/283 green when combined with prior commits
Still missing: plugin migration helper, docs page, live e2e test gated on
codex binary. Followup commits.
Teknium