The gateway dispatcher captured kanban.auto_decompose ONCE at boot, so a user
who flipped it to false to STOP auto-decompose had no way to make that take
effect short of restarting the gateway. Reported (#49638): auto-decompose
created and launched tasks the user never intended (while they were still
typing the task description), and 'even Hermes Agent couldn't disable this
feature' — because the live config edit was silently ignored.
Auto-decompose is a safety toggle; turning it off must halt fan-out on the
next tick. The dispatcher now re-reads the flag (and auto_decompose_per_tick)
from config every tick via the extracted _resolve_auto_decompose_settings(),
which fails SAFE (disabled) on a config read error so a transient failure can
never re-enable a feature the user turned off.
Closes#49638.
ruff (unspecified-encoding) and the Windows-footgun checker both flag
open() in text mode without encoture=. Keep text mode (the Windows lock
path in _try_acquire_file_lock writes a str newline) and pass
encoding='utf-8'.
Two robustness gaps from community review (#44919):
1. Windows dead-path: replaced bespoke fcntl.flock with gateway.status
_try_acquire_file_lock / _release_file_lock — already cross-platform
(msvcrt on Windows, fcntl on POSIX). Added _release_singleton_lock
helper.
2. Lock fd never released: stored handle is now released explicitly in
both exit paths — CancelledError handler and normal while-loop exit.
Allows in-process stop/restart (tests, embedded use).
Also tightened docstrings — 'corrupt the SQLite DBs' is now specific
(wal_autocheckpoint=0 + concurrent manual WAL checkpoints can corrupt
index pages), matching the module's own concurrency claims.
The gateway's embedded dispatcher has no guard against more than one dispatcher
running concurrently. dispatch_in_gateway defaults to true, so a second gateway
for the same profile (a restart race where the old process is slow to exit) — or
any deployment that runs multiple profile gateways with the default — starts a
second dispatcher loop. As #41448 describes, concurrent dispatchers each run
release_stale_claims() against the same boards, double reclaim frequency, and
re-dispatch slow workers before they finish. In practice they also corrupt the
shared kanban SQLite DBs under concurrent write load.
Add _acquire_singleton_lock(): an exclusive, non-blocking fcntl.flock at the
machine-global kanban root (kanban_home()/kanban/.dispatcher.lock — the board is
shared across profiles by design, so this serialises every gateway, not just one
profile). The first gateway to start its dispatcher holds the lock for its
process lifetime; any other gateway finds it contended, logs, and skips
dispatching while still running for messaging. Falls back to config-only control
on non-POSIX or filesystems without flock.
This is more robust than a per-profile guard because the documented model is
"one dispatcher sweeps all boards" — the contention is across profiles, not just
within one. Closes#41448.
Test: lock is exclusive (held, then contended while held, then held again after
release).
gateway/run.py is the largest god file (20k LOC, GatewayRunner with 220
methods). This lifts the cohesive kanban-watcher cluster — _kanban_notifier_watcher,
_kanban_dispatcher_watcher, _kanban_advance/unsub/rewind, _deliver_kanban_artifacts
(~1,035 LOC, 6 methods) — into gateway/kanban_watchers.py as a mixin that
GatewayRunner inherits.
Mixin (not free functions) because the methods use only self state: inheriting
keeps every self._kanban_* call site working unchanged via the MRO, making this
a behavior-neutral move. The methods' lazy imports (_kb, _decomp, _load_config,
Platform) travel with them; the mixin needs only stdlib + a matching
logging.getLogger('gateway.run').
run.py 20187 -> 19157 LOC; GatewayRunner direct methods 220 -> 214.
Behavior-neutral: gateway test suite 6582 passed / 0 failed; start() still wires
both watchers via self._kanban_*; MRO resolves all 6 to the mixin. One test
(corrupt-board quarantine retry) keyed its time-travel mock on the caller's
filename being gateway/run.py — updated to also accept gateway/kanban_watchers.py.
Establishes the mixin-extraction pattern for further GatewayRunner decomposition
(the 2406-LOC _run_agent and 1164-LOC _handle_message remain, but their callback
closures need a context-object redesign — deferred).
