fix(drop-stage): land the drop on intent main so haiku next doesn't hang

packages/haiku/src/statusline/state.ts

@@ -213,6 +213,13 @@ function describeAction(action: CursorAction | null): {
 	}
 	switch (action.kind) {
 		case "elaborate_loop":
+			// First arrival at an OPTIONAL stage surfaces a keep-or-drop
+			// decision (cursor stamps `optional_offer`). It's a gated choice,
+			// not mid-elaboration — render it distinctly so the strip shows
+			// the engine is waiting on the user/agent, not working.
+			if (action.optional_offer === true) {
+				return { kind: "elaborate", label: "keep / drop?", gated: true }
+			}
 			return { kind: "elaborate", label: "elaborate", gated: false }
 		case "start_unit_hat":
 			return { kind: "execute", label: "execute", gated: false }

packages/haiku/src/tools/orchestrator/haiku_drop_stage.ts

@@ -21,6 +21,7 @@
 
 import { existsSync, readFileSync } from "node:fs"
 import { join } from "node:path"
+import { deleteStageBranch, ensureOnStageBranch } from "../../git-worktree.js"
 import {
 	resolveIntentStages,
 	resolveStageOptional,
@@ -41,6 +42,7 @@ import {
 import {
 	findHaikuRoot,
 	gitCommitState,
+	isGitRepo,
 	parseFrontmatter,
 	setFrontmatterField,
 } from "../../state-tools.js"
@@ -131,8 +133,40 @@ export default defineTool({
 		const droppedIdx = planStages.indexOf(stage)
 		const nextStage = planStages[droppedIdx + 1]
 		const nextStages = planStages.filter((s) => s !== stage)
+
+		// Land the drop on INTENT MAIN — the fork source for every future
+		// stage branch (`ensureStageBranch` does `git branch <stage> <main>`).
+		// `intent.stages` is engine-owned FSM state; the keep-or-drop offer
+		// parked the checkout on the optional stage's own branch (the cursor's
+		// post-action branch switch), so a naive write would commit the drop
+		// there and strand it. The per-tick downstream sync only flows
+		// main → stage, and a dropped stage never completes (so it never
+		// merges up), so intent main would never see the drop: the next stage
+		// forks from a main that still lists the dropped stage, the cursor
+		// flip-flops dropped ⇆ next every tick, and the deadlock detector
+		// halts the loop — the "haiku next hangs after a drop" report.
+		//
+		// Guard 3 already proved the stage never started, so its branch holds
+		// no work to preserve. Switch back to intent main, write the drop
+		// there, then reap the abandoned optional-stage branch so it can't
+		// reassert the stale plan through a later sync. No-op in fs mode (no
+		// branches) — the single intent.md is authoritative as-is.
+		if (isGitRepo()) {
+			const mainGuard = ensureOnStageBranch(slug, undefined)
+			if (!mainGuard.ok) {
+				return text(
+					JSON.stringify({
+						error: "drop_stage_branch_switch_failed",
+						message: `Could not switch to intent main to land the drop of '${stage}': ${mainGuard.message}. Resolve the working-tree state (commit or stash any stray changes) and retry.`,
+					}),
+				)
+			}
+		}
 		setFrontmatterField(intentFile, "stages", nextStages)
 		gitCommitState(`haiku: drop optional stage ${stage} from ${slug}`)
+		// Reap the optional stage's now-orphaned branch (we're off it, on
+		// intent main). Best-effort — deleteStageBranch never throws.
+		if (isGitRepo()) deleteStageBranch(slug, stage)
 		emitTelemetry("haiku.stage.dropped", { intent: slug, stage, studio })
 
 		return text(

packages/haiku/test/drop-stage-lands-on-main.test.mjs

@@ -0,0 +1,152 @@
+// drop-stage-lands-on-main.test.mjs
+//
+// Regression for "haiku next hangs after a stage is dropped".
+//
+// The keep-or-drop offer parks the checkout on the optional stage's OWN
+// branch (the cursor's post-action branch switch). `haiku_drop_stage` used
+// to commit the `intent.stages` edit to whatever branch was checked out —
+// i.e. that doomed stage branch. But every future stage branch forks from
+// intent main (`git branch <stage> <main>`), and the per-tick sync only
+// flows main → stage, so intent main never saw the drop: the next stage
+// forked from a main that still listed the dropped stage, `findCurrentStage`
+// flip-flopped dropped ⇆ next every tick, and the deadlock detector halted
+// the loop (the "hang").
+//
+// The fix lands the drop on intent main and reaps the orphan stage branch.
+// This test proves both, plus that the cursor advances cleanly afterward.
+
+import assert from "node:assert/strict"
+import { execFileSync } from "node:child_process"
+import { mkdirSync, mkdtempSync, writeFileSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { dirname, join, resolve } from "node:path"
+import { test } from "node:test"
+import { fileURLToPath } from "node:url"
+
+const SRC = new URL("../src/", import.meta.url).pathname
+const __dirname = dirname(fileURLToPath(import.meta.url))
+// Point studio resolution at the repo's plugin dir — the test chdirs into a
+// temp repo, so cwd-relative studio lookup wouldn't find `software` otherwise.
+process.env.CLAUDE_PLUGIN_ROOT = resolve(__dirname, "..", "..", "..", "plugin")
+
+function git(cwd, ...args) {
+	execFileSync("git", args, { cwd, stdio: ["ignore", "pipe", "pipe"] })
+}
+
+function parseToolJson(res) {
+	return JSON.parse(res.content[0].text)
+}
+
+test("haiku_drop_stage lands the drop on intent main and reaps the stage branch", async () => {
+	const tmp = mkdtempSync(join(tmpdir(), "haiku-drop-stage-"))
+	git(tmp, "init", "-q")
+	git(tmp, "config", "user.email", "t@t.t")
+	git(tmp, "config", "user.name", "t")
+	git(tmp, "config", "commit.gpgsign", "false")
+	writeFileSync(join(tmp, "README.md"), "seed\n")
+	git(tmp, "add", "-A")
+	git(tmp, "commit", "-q", "-m", "seed")
+
+	const slug = "demo-drop"
+	// Build intent main with an intent whose plan reaches the optional
+	// `design` stage first (design is `optional: true` in the software
+	// studio; `development` after it is mandatory). No units / elaboration →
+	// `findCurrentStage` returns `design` and the drop guards all pass.
+	git(tmp, "checkout", "-q", "-b", `haiku/${slug}/main`)
+	const iDir = join(tmp, ".haiku", "intents", slug)
+	mkdirSync(iDir, { recursive: true })
+	writeFileSync(
+		join(iDir, "intent.md"),
+		[
+			"---",
+			"studio: software",
+			"mode: continuous",
+			"stages:",
+			"  - design",
+			"  - development",
+			"title: demo drop",
+			"status: active",
+			"---",
+			"",
+			"Drop-stage regression fixture.",
+			"",
+		].join("\n"),
+	)
+	git(tmp, "add", "-A")
+	git(tmp, "commit", "-q", "-m", "intent")
+
+	// Fork the optional stage's branch from main and park the checkout on it
+	// — exactly the state the post-cursor branch switch leaves us in when the
+	// keep-or-drop offer is handed to the agent.
+	git(tmp, "branch", `haiku/${slug}/design`, `haiku/${slug}/main`)
+	git(tmp, "checkout", "-q", `haiku/${slug}/design`)
+
+	const orig = process.cwd()
+	process.chdir(tmp)
+	try {
+		const { getCurrentBranch, branchExists } = await import(
+			`${SRC}git-worktree.ts`
+		)
+		const { findCurrentStage } = await import(
+			`${SRC}orchestrator/workflow/cursor.ts`
+		)
+		// Sanity: we really are parked on the doomed stage branch, and the
+		// cursor sees `design` as active.
+		assert.equal(getCurrentBranch(), `haiku/${slug}/design`)
+		assert.equal(findCurrentStage(slug, "software"), "design")
+
+		const dropTool = (
+			await import(`${SRC}tools/orchestrator/haiku_drop_stage.ts`)
+		).default
+		const res = parseToolJson(
+			await dropTool.handle({ intent: slug, stage: "design" }),
+		)
+		assert.equal(
+			res.action,
+			"stage_dropped",
+			`unexpected: ${JSON.stringify(res)}`,
+		)
+		assert.deepEqual(res.stages, ["development"])
+
+		// 1. The drop landed on intent MAIN (the fork source), and the
+		//    checkout was moved back there.
+		assert.equal(
+			getCurrentBranch(),
+			`haiku/${slug}/main`,
+			"drop must leave the checkout on intent main",
+		)
+		const mainIntent = execFileSync(
+			"git",
+			["show", `haiku/${slug}/main:.haiku/intents/${slug}/intent.md`],
+			{ cwd: tmp, encoding: "utf8" },
+		)
+		assert.match(
+			mainIntent,
+			/stages:\s*\n\s*-\s*development\s*\n/,
+			"intent main's plan must drop `design` and keep `development`",
+		)
+		assert.ok(
+			!/-\s*design/.test(mainIntent),
+			"`design` must be gone from intent main's plan",
+		)
+
+		// 2. The orphan stage branch is reaped — it can no longer reassert the
+		//    stale plan through a downstream sync.
+		assert.equal(
+			branchExists(`haiku/${slug}/design`),
+			false,
+			"the dropped stage's branch must be deleted",
+		)
+
+		// 3. The cursor advances to the next stage with no oscillation: from
+		//    intent main (which now carries the drop) `findCurrentStage`
+		//    returns `development`, never `design`.
+		assert.equal(
+			findCurrentStage(slug, "software"),
+			"development",
+			"cursor must advance to the next stage, not flip back to the dropped one",
+		)
+	} finally {
+		process.chdir(orig)
+	}
+})