宜博 / lemongraph

New target projects never got .claude/agents/*.md deployed, so their first
Planner call always failed immediately (claude --agent planner finds nothing
in cwd) -- self-target usage never noticed since those files are already
committed as part of this repo. create_project() now deploys and commits
them alongside the existing .graphlemon/ init commit.

Also: unroutable execution failures were recorded as a bare
blocked_reason='execution_error' with no way to see what actually broke.
scheduler._block_task()/task_execution._mark_blocked() now persist the real
exception message into execution_event.payload (blocked_reason itself is
unchanged -- budget_guardrail matches its exact value elsewhere).

Found via a real console Start-button failure on a freshly created project;
see docs/implementation-gap-analysis.md for the full writeup.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Users had no way to actually start a queued goal from the console --
task.status just sits at 'queued' forever. Traced the root cause through
03-C: c_task_create's own contract ("若 max_concurrent_goals 已达上限，
任务落 queued 但不触发调度") implies task creation auto-triggers
scheduling otherwise, and 03-C/04-P repeatedly assume an always-on Org
Graph scheduler that watches the queue -- src/scheduler.py builds the
mechanism but nothing ever spins it up as a running process, so no
"start" button was ever designed because none was supposed to be needed.

Design (confirmed with user, both recommended options chosen):
- Pause/Stop are a soft stop, not a real subprocess kill -- the current
  in-flight `claude` call finishes naturally, only the next phase is
  withheld. Hard-killing would need Popen + PID tracking, out of scope.
- No new task.status enum value -- reuses blocked_pending_human with
  blocked_reason='user_paused'/'user_stopped', riding the existing
  manual_resume mechanism instead of a schema change.

New src/task_execution.py: run_or_resume_task_lifecycle() resumes from
whichever phase actually hasn't run yet (queued/planning_brd_prd_sdd/
coding), start_task_execution_in_background() runs it to completion on
its own daemon thread + sqlite connection, request_pause() blocks an
in-flight task. Extended /route's manual_resume handling so resuming
from a user-initiated pause/stop actually re-continues execution in the
background, not just flips the status field back.

Real gap found while building this: backend_server.create_server() never
stored db_path on the server object -- needed for the new background
thread to open its own connection to the same db.

22 new tests (14 src/test_task_execution.py + 8 TaskExecutionRouteTest in
test_backend_server.py, HTTP wiring mocked around the already-unit-tested
background thread mechanics). Verified against a real running server via
curl: /execute 409s a non-queued task, /pause 409s a queued task and a
double-pause, succeeds on a coding task. src/ suite: 496 tests, all green.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>