fix(runtime): hold an agy composer whose draft reads like an edit mode (#39296)

A draft such as `dark mode: fix the toggle`, or agy's plan placeholder typed
verbatim, matches the composer caret row's edit-mode alternative. agy hides
`? for shortcuts` while the composer holds text, so composer_ready refused,
but composer_ready_custom_status_line (#38930) took agy's own
`[mode · ]model · effort` footer for a custom status row and answered idle.
Orca would then paste into the operator's unsent text.

Status rows may no longer be agy's built-in footer. The captured agy 1.2.7
screen of the plan placeholder typed as a draft comes from #23402.

Split from #23402.

Co-authored-by: seonghobae <8172694+seonghobae@users.noreply.github.com>

src/main/runtime/__fixtures__/antigravity-plan-hint-as-draft-127.meta.json

@@ -0,0 +1,9 @@
+{
+  "capturedAt": "2026-09-19T07:34:50.080Z",
+  "platform": "darwin",
+  "command": ["agy", "--mode", "plan"],
+  "cols": 120,
+  "rows": 40,
+  "note": "Plan mode; exact placeholder wording typed as an unsent draft at 12 seconds",
+  "exitCode": 0
+}

src/main/runtime/__fixtures__/antigravity-plan-hint-as-draft-127.txt

@@ -0,0 +1,13 @@
+_Ga=q,f=32,s=1,v=1,i=31;AAAAAA==\[?2026$p[?2027$p[?5W[?2004h[>4;2m[>1u[?u[0 q␍
+▄▀▀▄        Antigravity CLI 1.2.7
+▀▀▀▀▀▀       Gemini API key
+▀▀▀▀▀▀▀▀      Gemini 3.7 Flash (Low)
+   ▄▀▀    ▀▀▄     ~/orca/workspaces/orca/agy-gemini-issues
+  ▄▀▀      ▀▀▄
+
+────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
+> Plan mode: research & plan only (shift+tab to cycle)
+────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
+? for shortcutsplan · Gemini 3.7 Flash · low␍[?25h[?25lPlan
+
+ p[?25h[?25lmode: re[?25h[?25lsearch[?25h[?25l& plan[?25h[?25l only (s[?25h[?25lhift+ta[?25h[?25lb to cy[?25h[?25lcle)[?25h

src/main/runtime/agent-state-rules/antigravity-composer-draft.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'vitest'
+import { finalReplayFrame } from '../agent-transcript-replay-test-harness'
+import { evaluateAgentStateRules } from './agent-state-rules-engine'
+
+const verdict = (lines: readonly string[]) =>
+  evaluateAgentStateRules('antigravity', { readScreenLines: () => lines })?.state
+
+describe('an Antigravity composer holding a mode-shaped draft', () => {
+  it('holds when agy 1.2.7 shows the plan placeholder typed as unsent text', async () => {
+    const { ruledScreenLines } = await finalReplayFrame(
+      'antigravity-plan-hint-as-draft-127',
+      120,
+      40
+    )
+    expect(verdict(ruledScreenLines)).toBe('hold')
+  })
+
+  it('holds for a draft that only reads like an edit mode', () => {
+    const rule = '─'.repeat(40)
+    expect(verdict([rule, '> dark mode: fix the toggle', rule, 'Gemini 3.7 Flash · low'])).toBe(
+      'hold'
+    )
+  })
+})

src/main/runtime/agent-state-rules/antigravity.json

@@ -28,7 +28,7 @@
     },
     {
       "id": "composer_ready_custom_status_line",
-      "why": "A custom statusLine paints its own rows where the hint row was, so `esc to cancel` never shows. agy 1.5.2 then marks a turn only with a braille spinner row right above the composer. Status rows may hold no rule run, hint or busy hint, so hint-row layouts and garbled grids cannot match, and pickers drawn between the composer and the status rows break the run of rows.",
+      "why": "A custom statusLine replaces the hint row, so `esc to cancel` never shows; agy 1.5.2 then marks a turn only with a braille spinner row above the composer. Status rows may not hold a rule run, a hint, or agy's own `[mode · ]model · effort` footer, which drops its hint while the composer holds a draft. Pickers between the composer and status rows break the run. A custom row shaped like that footer holds; a mode-shaped draft above a custom statusLine still reads idle.",
       "priority": 400,
       "when": {
         "region": "screen",
@@ -41,7 +41,8 @@
             "optional": {
               "none": [
                 { "regex": "──" },
-                { "regex": "esc to cancel|for shortcuts", "ignoreCase": true }
+                { "regex": "esc to cancel|for shortcuts", "ignoreCase": true },
+                { "regex": "^(?:[a-z][a-z-]* · )?[^·]+ · (?:low|medium|high)$" }
               ]
             }
           },
@@ -49,14 +50,16 @@
             "optional": {
               "none": [
                 { "regex": "──" },
-                { "regex": "esc to cancel|for shortcuts", "ignoreCase": true }
+                { "regex": "esc to cancel|for shortcuts", "ignoreCase": true },
+                { "regex": "^(?:[a-z][a-z-]* · )?[^·]+ · (?:low|medium|high)$" }
               ]
             }
           },
           {
             "none": [
               { "regex": "──" },
-              { "regex": "esc to cancel|for shortcuts", "ignoreCase": true }
+              { "regex": "esc to cancel|for shortcuts", "ignoreCase": true },
+              { "regex": "^(?:[a-z][a-z-]* · )?[^·]+ · (?:low|medium|high)$" }
             ]
           }
         ]