U12: resolve the move-path compatibility flag — trait hooks unconditional, legacy branch deleted (#2655)

U12's headline goal. The raw `experimentalFeatures.workflowColumns` flag
gated **every task move**; its six seams are now unconditional and the
flag, its last two readers, and the 124-line inline legacy branch are
deleted.

## Deleted, not converted

The flag-OFF branch goes with the gate. Converting a branch we intended
to delete would have left a second definition of every column side
effect alive to drift — the defect this program has spent its length
removing.

Both readers flip in **one commit** because they are not separable: the
preflight in `workflow-task-create-ops.ts` computes the
`movePolicyPreflight` that `moves.ts` consumes and validates. Un-gating
either alone either evaluates workflow move policies — with their
plugin-gate side effects — whose result is ignored, or validates against
a preflight that was never computed.

## Evidence, not assertion

**Equivalence (precondition 1).** `moves-flag-equivalence.test.ts`
(commit 1) ran the same journey under both flag states against live
PostgreSQL and diffed the persisted row: **identical across 128 fields**
plus an equal timing shape, over `todo → in-progress → in-review → todo
→ in-progress`. Mutation-verified both ways — stamping the flag-ON
branch, and diverging the reopen hook, each fail it.

**And there was stronger evidence already on main that isn't mine.**
U2b's `move-path-equivalence.pg.test.ts` ran *every* scenario once per
path and has been green across ~10 of them: `preserveStatus`,
`preservePause`, timing accounting, `preserveProgress`,
`preserveWorktree`, engine-source rehome, `in-progress → todo`. Two
independently built harnesses agreeing is the best evidence this
question has had.

**The flag was read by nothing in production.** `experimentalFeatures`
is global-only and no module writes it, so this path had never run for
any project without a stale persisted value. That is also why a green
suite was never evidence on its own — both paths were individually valid
and only one was live.

## Two claims of mine this PR corrects

**1. Seam 2 does not introduce new rejections.** I said in #2639 and in
the census that with the flag off there is *no* target validation, so
flipping would add refusals. Reproduced the opposite: a move to an
undeclared column already rejects on the legacy path with `Invalid
transition: … Valid targets: …`. I found it because the discriminator I
wrote to prove "the flag is the cause" failed.

**2. My first equivalence test proved nothing.** It used
`updateSettings`; `experimentalFeatures` is **global-only**, so
`getSettingsFast()` filtered the write out and `useWorkflow` was false
in *both* runs. Caught by stamping the flag-ON branch and watching the
test stay green. It now writes via `updateGlobalSettings` and **asserts
the flag took effect** before the journey. U2b's harness carries the
same warning independently — `MUST be updateGlobalSettings, NOT
updateSettings`.

## The user-visible change

Move rejections now report **workflow-resolved** targets instead of the
hardcoded legacy adjacency table. Concretely: `Valid targets:
in-progress, triage, archived` becomes `Valid targets: archived,
in-progress`. That is the fix, not a regression — the legacy table still
advertised `triage`, a column the default lineage stopped declaring at
#2515, so an operator following the old message was told to move
somewhere impossible.

Likewise a move *into* `triage` is now refused rather than stranding the
card in a column with no trait flags, invisible to every trait-driven
sweep until reconciliation re-homes it.
`live-move-path-undeclared-target.test.ts` characterised exactly that
defect and carried `it.todo("should REFUSE a move into a column the
task's workflow does not declare (U2b)")` — **this fulfils it.**

## Test migration

| file | change |
|---|---|
| `move-path-equivalence.pg.test.ts` | deleted — every scenario ran once
per path; purpose fully discharged |
| `workflow-capacity-invariant.pg.test.ts` |
`setPath("inline"\|"hooks")` → `assertMovePathLive()`; the probe is
**kept** so capacity cannot pass because moves were broken for an
unrelated reason |
| `store-movement.pg.test.ts` | asserts the refusal **and** that the
legitimate backward move still works, so it reads as a narrowing |
| `raw-workflow-columns-flag-census.test.ts` | deleted per its own
instructions — it was built to fail in both directions and fired exactly
as designed: `expected [] to deeply equal [3 readers]` |
| `moves-workflow-flag-seams.test.ts` | deleted — it pinned the six
seams this removes |

## Verification

Full core suite: **33 failed / 10 files — byte-identical to main's
baseline**, with **zero** files failing exclusively on this branch. I
measured the baseline by checking out `origin/main` and running the same
command, because the first comparison I made was by count alone and
would have blamed the flip for 8 files that were already red.

`pnpm lint` clean. `pnpm test:gate` green (10 / 132 / 482 / 71). `tsc -p
packages/core/tsconfig.json` clean. Core builds.

## Left in place deliberately

The `workflowColumns` settings key stays schema-tolerated and is already
in `HIDDEN_EXPERIMENTAL_FEATURE_KEYS`, so an upgraded project carrying a
stale value renders nothing and loads cleanly. Removing it from the
schema would risk rejecting those projects for no benefit now that
nothing reads it.

---

## Rebased onto current main — and `triage` reaches ZERO

| metric | before | after |
|---|---:|---:|
| `moves.ts` column guards | 39 | **15** |
| repo column total | 745 | **741** |
| **`triage` column guards** | 1 | **ABSENT (0)** |

`triage` is now absent from `byColumnId` entirely: no unconverted
`triage` guard remains anywhere in production source. Combined with
#2664 (the last one, in `TaskContextMenu`) this closes bar item 1.

The census behaved exactly as designed on the rebase: the flip *deletes*
guards, so `--strict` reported `moves.ts: allows 39, tree has 15` rather
than leaving a stale allowance, and the re-record lands in this PR's
diff.

## Verification on the rebased tree

- Full core suite: **33 failed / 10 files — identical to main's
baseline**, zero files failing exclusively on this branch (measured by
checking out `origin/main` and diffing the failing-file sets, not by
comparing counts).
- `pnpm test:gate` green (10 / 158 / 487 / 71).
- `pnpm check:lifecycle-columns` exits 0.
- `pnpm lint` clean, `@fusion/core` builds.

## Two review fixes carried in this PR

**P1 — optionless engine moves lost their bypass.**
`resolveWorkflowBypassGuardsImpl` did `void moveSource;` — it discarded
the resolved parameter and re-read `options?.moveSource`, so
`moveTask(id, target)` resolved to `"engine"` at the call site and
computed `bypassGuards === false`. Latent while the flag gated
validation; with the gate gone, an internal executor/merger/recovery
move made without an options object would be judged as a user move.

**P2 — the absence signal.** Emitting `workflowId` unconditionally would
have stamped `builtin:coding` onto every task with no explicit
selection, reporting a fallback as authoritative. Now emits the
selection directly, so absent still means "not resolved here".


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
  - Task moves are now validated against the task’s declared workflow.
- Invalid destinations are rejected with a clear error, and tasks remain
in their original column.
  - Valid backward moves continue to work as expected.
- Move behavior and lifecycle updates are now handled consistently
across workflows.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/lib/lifecycle-column-census-baseline.json

@@ -1,27 +1,26 @@
 {
   "generatedFrom": "node scripts/lifecycle-column-census.mjs --strict --update-baseline",
   "totals": {
-    "column": 746,
+    "column": 722,
     "role": 5,
     "status": 186,
     "deliberate": 17
   },
   "byColumnId": {
-    "done": 199,
-    "in-progress": 144,
-    "in-review": 205,
+    "done": 195,
+    "in-progress": 138,
+    "in-review": 200,
     "archived": 147,
-    "todo": 47,
-    "triage": 4
+    "todo": 42
   },
   "byFile": {
     "packages/engine/src/self-healing.ts": 110,
     "packages/engine/src/executor.ts": 85,
     "packages/dashboard/app/components/TaskCard.tsx": 42,
-    "packages/core/src/task-store/moves.ts": 39,
     "packages/dashboard/app/components/TaskDetailModal.tsx": 30,
     "packages/engine/src/scheduler.ts": 28,
     "packages/dashboard/src/routes/register-task-workflow-routes.ts": 20,
+    "packages/core/src/task-store/moves.ts": 15,
     "packages/core/src/store.ts": 12,
     "packages/engine/src/project-engine.ts": 12,
     "packages/engine/src/mission-execution-loop.ts": 10,