docs(pilot): correct Phase 9 migration description

Handoff + migration spec incorrectly claimed Phase 9 added a new
parent_pilot_session_id FK. The implementation reuses the existing
ai_session_id column; the migration only adds the origin discriminator
+ partial unique index. Also: ScriptBuilderTab wraps ScriptBuilderChat
and ScriptBodyEditor (Monaco), not "ScriptBuilderChat in ephemeral
mode" — there is no ephemeral mode on the presentational component.

Applies applied_at call-site specifics: handleScriptDecision stamps
on one_off/draft_template, TemplateMatchPanel stamps on onMarkRun,
Script Builder tab Submit does not stamp.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/handoff/2026-04-22-flowpilot-migration.md

@@ -29,7 +29,7 @@ All nine migration phases are merged onto the branch and verified against the li
 | 6 — post-resolve templatize | `4aaf57a` | `draft_templates` table, accept/reject endpoints, `TemplatizePrompt` modal, account preferences |
 | 7 — polish | `8a242f5` | loading/empty states, keyboard shortcuts (`⌘↵`, `⌘G`, `?` overlay), responsive bottom-drawer <1200px |
 | 8 — Fix Outcome Banner | `cdd8bb0`..`a47ce07` | Six outcome columns on `session_suggested_fixes` (`status`, `applied_at`, `verified_at`, `partial_notes`, `failure_reason`, `ai_outcome_proposal`) + `PATCH /api/v1/ai-sessions/{sid}/suggested-fixes/{fid}/outcome` endpoint + `[FIX_OUTCOME]` marker; replaces task-lane `SuggestedFix` card with a chat-composer-anchored `ProposalBanner` (5 states: proposed/verifying/partial/ai_confirming/nudge + collapsed); `EscalateInterceptDialog` captures outcome before handoff; Resolve-while-verifying auto-marks success; 17 new tests (8 endpoint + 7 marker + 2 anti-parrot) |
-| 9 — Tabbed Script Builder | `5bcb7aa`..`faf1d8d` | Chat-region tab strip (`[Chat] [Script Builder ●]`) with `ChatTabStrip` + `ScriptBuilderTab` (inline `ScriptBuilderChat` in ephemeral mode); `InlineNoTemplateDialog` relocated from task-lane `bottomSlot` to a chat-region placement wrapper; `EscalateInterceptDialog` gains a fourth "partial attempt" choice; `PATCH /api/v1/ai-sessions/{id}/suggested-fixes/{fid}/script` endpoint for writing back AI-drafted script; Alembic migration adds `origin` column + `parent_pilot_session_id` FK to `script_builder_sessions` with partial unique index; `applied_at` semantics corrected to stamp only on run-declaring actions (not the Apply click) |
+| 9 — Tabbed Script Builder | `5bcb7aa`..`faf1d8d` | Chat-region tab strip (`[Chat] [Script Builder ●]`) with `ChatTabStrip` + new `ScriptBuilderTab` controller wrapping the existing `ScriptBuilderChat` + Monaco editor (`ScriptBodyEditor`); `InlineNoTemplateDialog` relocates the existing `NoTemplateDialog` from the narrow task-lane `bottomSlot` to a chat-region placement wrapper; `EscalateInterceptDialog` gains a fourth "partial" choice; `PATCH /api/v1/ai-sessions/{sid}/suggested-fixes/{fid}/script` endpoint for engineer-drafted scripts (does not stamp `applied_at`); Alembic migration adds `origin VARCHAR(20)` to `script_builder_sessions` (reuses existing `ai_session_id` FK) + partial unique index on `(user_id, ai_session_id) WHERE origin='pilot_inline'` for idempotent get-or-create; `applied_at` semantics corrected to stamp only on run-declaring actions (`handleScriptDecision` for `one_off`/`draft_template`; new `onMarkRun` on `TemplateMatchPanel`) — not the Apply click |
 
 Plus the structural fixes that came up along the way:
 - `50215b9` + `d0ebdef` — full sweep removing literal payloads from AI system prompts; new `tests/test_prompt_anti_parrot.py` guardrail
@@ -63,11 +63,11 @@ See [docs/FlowAssist_Migration/phase-8-fix-outcome-banner.md](../FlowAssist_Migr
 ### 3. Tabbed Script Builder inside the chat (Option A from the modal-vs-tab discussion)
 **Status: RESOLVED by Phase 9.**
 
-Phase 9 shipped the complete tabbed Script Builder integration. The chat region now has a `[Chat] [Script Builder ●]` tab strip (`ChatTabStrip`) powered by `ScriptBuilderTab`, which embeds `ScriptBuilderChat` in ephemeral mode (returns script to caller, no standalone `script_templates` row). `display: none` toggling preserves chat scroll position, draft message, and history across tab switches.
+Phase 9 shipped the complete tabbed Script Builder integration. The chat region now has a `[Chat] [Script Builder ●]` tab strip (`ChatTabStrip`) powered by a new `ScriptBuilderTab` controller that wraps the existing (untouched) `ScriptBuilderChat` for AI mode and `ScriptBodyEditor` (Monaco) for a "Write it myself" editor mode. `display: none` toggling preserves chat scroll position, draft message, and editor buffer across tab switches.
 
-The `PATCH /api/v1/ai-sessions/{id}/suggested-fixes/{fid}/script` endpoint writes `ai_drafted_script` + `ai_drafted_parameters` back to the fix record so the three-option dialog unlocks normally after script generation.
+The `PATCH /api/v1/ai-sessions/{sid}/suggested-fixes/{fid}/script` endpoint writes `ai_drafted_script` + `ai_drafted_parameters` back to the fix record without stamping `applied_at` — a draft is not an application. Bumps `state_version` so cached Resolve/Escalate previews regenerate.
 
-The migration added `origin VARCHAR(20) DEFAULT 'standalone'` and `parent_pilot_session_id UUID NULL REFERENCES ai_sessions(id)` to `script_builder_sessions`, with a partial unique index ensuring only one active inline session per pilot session.
+The migration added `origin VARCHAR(20) NOT NULL DEFAULT 'standalone'` (with CHECK constraint on the two valid values + invariant that `origin='pilot_inline'` requires `ai_session_id IS NOT NULL`) to `script_builder_sessions`. It reuses the pre-existing `ai_session_id` FK rather than adding a new parent column. A partial unique index on `(user_id, ai_session_id) WHERE origin='pilot_inline'` backs get-or-create idempotency from the inline tab.
 
 See [docs/FlowAssist_Migration/phase-9-implementation-plan.md](../FlowAssist_Migration/phase-9-implementation-plan.md) and [docs/FlowAssist_Migration/phase-9-script-builder-tab.md](../FlowAssist_Migration/phase-9-script-builder-tab.md) for full implementation details.
 
@@ -75,7 +75,7 @@ See [docs/FlowAssist_Migration/phase-9-implementation-plan.md](../FlowAssist_Mig
 
 - **PR not opened.** Branch is pushed but no Gitea PR yet. When ready: `gh pr create` works against the GitHub mirror, but the actual review happens in Gitea.
 - **`/ultrareview` not run** on the final state of the branch (including Phase 9). Worth doing before PR creation.
-- **Phase 9 browser QA not done.** The new tab strip, `ScriptBuilderTab`, `InlineNoTemplateDialog` chat-region placement, and `EscalateInterceptDialog` fourth-choice flow have not been exercised in a headless-browser session. Key states to cover: tab strip renders and toggles without unmounting chat; ephemeral Script Builder returns a script and unlocks the three-option dialog; partial-attempt choice in `EscalateInterceptDialog` is recorded correctly.
+- **Phase 9 browser QA not done.** The new tab strip, `ScriptBuilderTab` (AI + editor modes), `InlineNoTemplateDialog` chat-region placement, and `EscalateInterceptDialog` fourth-choice flow have not been exercised in a headless-browser session. Key states to cover: tab strip renders and toggles without unmounting chat or losing editor buffer; Script Builder tab Submit persists script via PATCH without stamping `applied_at`; `one_off`/`draft_template` decisions DO stamp; `build_template` does NOT stamp; `TemplateMatchPanel` "I ran this" stamps via `onMarkRun`; partial-attempt choice in `EscalateInterceptDialog` is recorded correctly.
 - **Phase 8 browser QA not done.** The `ProposalBanner` and `EscalateInterceptDialog` (three-choice variant) have not been exercised in a headless-browser session. Key states: banner appears on `[FIX_OUTCOME]` marker; banner dismisses correctly; escalate mid-fix triggers dialog; banner auto-collapses after session resolved. Use `/qa` or `/design-review` against `mockups/06-slide-up-banner.html` and `mockups/07-verify-states.html`.
 - **Phase 7 visual verification was structural only** — `tsc -b` and `npm run build` both clean, HMR applied each change without error, but no headless-browser screenshot comparison against the mockup PNGs. If you want pixel-level verification, `/qa` or `/design-review` would catch deltas.
 - **Anti-parrot test runs as part of `pytest`** but is not enforced in any specific CI step yet — verify `tests/test_prompt_anti_parrot.py` is discovered by the existing pytest run, and consider failing CI explicitly on regression.