Merge pull request #1941 from code-yeongyu/fix/issue-1939-initial-pane-spawn

fix(tmux): skip agent area width guard when 0 agent panes exist

src/cli/run/completion-verbose-logging.test.ts

@@ -0,0 +1,78 @@
+import { describe, it, expect, mock, spyOn } from "bun:test"
+import type { RunContext, ChildSession, SessionStatus } from "./types"
+
+const createMockContext = (overrides: {
+  childrenBySession?: Record<string, ChildSession[]>
+  statuses?: Record<string, SessionStatus>
+  verbose?: boolean
+} = {}): RunContext => {
+  const {
+    childrenBySession = { "test-session": [] },
+    statuses = {},
+    verbose = false,
+  } = overrides
+
+  return {
+    client: {
+      session: {
+        todo: mock(() => Promise.resolve({ data: [] })),
+        children: mock((opts: { path: { id: string } }) =>
+          Promise.resolve({ data: childrenBySession[opts.path.id] ?? [] })
+        ),
+        status: mock(() => Promise.resolve({ data: statuses })),
+      },
+    } as unknown as RunContext["client"],
+    sessionID: "test-session",
+    directory: "/test",
+    abortController: new AbortController(),
+    verbose,
+  }
+}
+
+describe("checkCompletionConditions verbose waiting logs", () => {
+  it("does not print busy waiting line when verbose is disabled", async () => {
+    // given
+    const consoleLogSpy = spyOn(console, "log").mockImplementation(() => {})
+    consoleLogSpy.mockClear()
+    const ctx = createMockContext({
+      childrenBySession: {
+        "test-session": [{ id: "child-1" }],
+        "child-1": [],
+      },
+      statuses: { "child-1": { type: "busy" } },
+      verbose: false,
+    })
+    const { checkCompletionConditions } = await import("./completion")
+
+    // when
+    const result = await checkCompletionConditions(ctx)
+
+    // then
+    expect(result).toBe(false)
+    expect(consoleLogSpy).not.toHaveBeenCalled()
+  })
+
+  it("prints busy waiting line when verbose is enabled", async () => {
+    // given
+    const consoleLogSpy = spyOn(console, "log").mockImplementation(() => {})
+    consoleLogSpy.mockClear()
+    const ctx = createMockContext({
+      childrenBySession: {
+        "test-session": [{ id: "child-1" }],
+        "child-1": [],
+      },
+      statuses: { "child-1": { type: "busy" } },
+      verbose: true,
+    })
+    const { checkCompletionConditions } = await import("./completion")
+
+    // when
+    const result = await checkCompletionConditions(ctx)
+
+    // then
+    expect(result).toBe(false)
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      expect.stringContaining("Waiting: session child-1... is busy")
+    )
+  })
+})

src/cli/run/completion.ts

@@ -12,7 +12,7 @@ export async function checkCompletionConditions(ctx: RunContext): Promise<boolea
 
     if (continuationState.hasActiveHookMarker) {
       const reason = continuationState.activeHookMarkerReason ?? "continuation hook is active"
-      console.log(pc.dim(`  Waiting: ${reason}`))
+      logWaiting(ctx, reason)
       return false
     }
 
@@ -24,7 +24,7 @@ export async function checkCompletionConditions(ctx: RunContext): Promise<boolea
       return false
     }
 
-    if (!areContinuationHooksIdle(continuationState)) {
+    if (!areContinuationHooksIdle(ctx, continuationState)) {
       return false
     }
 
@@ -35,14 +35,17 @@ export async function checkCompletionConditions(ctx: RunContext): Promise<boolea
   }
 }
 
-function areContinuationHooksIdle(continuationState: ContinuationState): boolean {
+function areContinuationHooksIdle(
+  ctx: RunContext,
+  continuationState: ContinuationState
+): boolean {
   if (continuationState.hasActiveBoulder) {
-    console.log(pc.dim("  Waiting: boulder continuation is active"))
+    logWaiting(ctx, "boulder continuation is active")
     return false
   }
 
   if (continuationState.hasActiveRalphLoop) {
-    console.log(pc.dim("  Waiting: ralph-loop continuation is active"))
+    logWaiting(ctx, "ralph-loop continuation is active")
     return false
   }
 
@@ -61,7 +64,7 @@ async function areAllTodosComplete(ctx: RunContext): Promise<boolean> {
   )
 
   if (incompleteTodos.length > 0) {
-    console.log(pc.dim(`  Waiting: ${incompleteTodos.length} todos remaining`))
+    logWaiting(ctx, `${incompleteTodos.length} todos remaining`)
     return false
   }
 
@@ -96,9 +99,7 @@ async function areAllDescendantsIdle(
   for (const child of children) {
     const status = allStatuses[child.id]
     if (status && status.type !== "idle") {
-      console.log(
-        pc.dim(`  Waiting: session ${child.id.slice(0, 8)}... is ${status.type}`)
-      )
+      logWaiting(ctx, `session ${child.id.slice(0, 8)}... is ${status.type}`)
       return false
     }
 
@@ -114,3 +115,11 @@ async function areAllDescendantsIdle(
 
   return true
 }
+
+function logWaiting(ctx: RunContext, message: string): void {
+  if (!ctx.verbose) {
+    return
+  }
+
+  console.log(pc.dim(`  Waiting: ${message}`))
+}

src/cli/run/runner.ts

@@ -9,6 +9,7 @@ import { executeOnCompleteHook } from "./on-complete-hook"
 import { resolveRunAgent } from "./agent-resolver"
 import { pollForCompletion } from "./poll-for-completion"
 import { loadAgentProfileColors } from "./agent-profile-colors"
+import { suppressRunInput } from "./stdin-suppression"
 
 export { resolveRunAgent }
 
@@ -53,11 +54,15 @@ export async function run(options: RunOptions): Promise<number> {
       serverCleanup()
     }
 
-    process.on("SIGINT", () => {
+    const restoreInput = suppressRunInput()
+    const handleSigint = () => {
       console.log(pc.yellow("\nInterrupted. Shutting down..."))
+      restoreInput()
       cleanup()
       process.exit(130)
-    })
+    }
+
+    process.on("SIGINT", handleSigint)
 
     try {
       const sessionID = await resolveSession({
@@ -124,6 +129,9 @@ export async function run(options: RunOptions): Promise<number> {
     } catch (err) {
       cleanup()
       throw err
+    } finally {
+      process.removeListener("SIGINT", handleSigint)
+      restoreInput()
     }
   } catch (err) {
     if (jsonManager) jsonManager.restore()

src/cli/run/stdin-suppression.test.ts

@@ -0,0 +1,89 @@
+import { describe, it, expect, mock } from "bun:test"
+import { EventEmitter } from "node:events"
+import { suppressRunInput } from "./stdin-suppression"
+
+type FakeStdin = EventEmitter & {
+  isTTY?: boolean
+  isRaw?: boolean
+  setRawMode: ReturnType<typeof mock<(mode: boolean) => void>>
+  isPaused: ReturnType<typeof mock<() => boolean>>
+  resume: ReturnType<typeof mock<() => void>>
+  pause: ReturnType<typeof mock<() => void>>
+}
+
+function createFakeStdin(options: {
+  isTTY?: boolean
+  isRaw?: boolean
+  paused?: boolean
+} = {}): FakeStdin {
+  const emitter = new EventEmitter() as FakeStdin
+  emitter.isTTY = options.isTTY ?? true
+  emitter.isRaw = options.isRaw ?? false
+  emitter.setRawMode = mock((mode: boolean) => {
+    emitter.isRaw = mode
+  })
+  emitter.isPaused = mock(() => options.paused ?? false)
+  emitter.resume = mock(() => {})
+  emitter.pause = mock(() => {})
+  return emitter
+}
+
+describe("suppressRunInput", () => {
+  it("ignores non-tty stdin", () => {
+    // given
+    const stdin = createFakeStdin({ isTTY: false })
+    const onInterrupt = mock(() => {})
+
+    // when
+    const restore = suppressRunInput(stdin, onInterrupt)
+    restore()
+
+    // then
+    expect(stdin.setRawMode).not.toHaveBeenCalled()
+    expect(stdin.resume).not.toHaveBeenCalled()
+    expect(onInterrupt).not.toHaveBeenCalled()
+  })
+
+  it("enables raw mode and restores it", () => {
+    // given
+    const stdin = createFakeStdin({ isRaw: false, paused: true })
+
+    // when
+    const restore = suppressRunInput(stdin)
+    restore()
+
+    // then
+    expect(stdin.setRawMode).toHaveBeenNthCalledWith(1, true)
+    expect(stdin.resume).toHaveBeenCalledTimes(1)
+    expect(stdin.setRawMode).toHaveBeenNthCalledWith(2, false)
+    expect(stdin.pause).toHaveBeenCalledTimes(1)
+  })
+
+  it("calls interrupt handler on ctrl-c", () => {
+    // given
+    const stdin = createFakeStdin()
+    const onInterrupt = mock(() => {})
+    const restore = suppressRunInput(stdin, onInterrupt)
+
+    // when
+    stdin.emit("data", "\u0003")
+    restore()
+
+    // then
+    expect(onInterrupt).toHaveBeenCalledTimes(1)
+  })
+
+  it("does not call interrupt handler on arrow-key escape", () => {
+    // given
+    const stdin = createFakeStdin()
+    const onInterrupt = mock(() => {})
+    const restore = suppressRunInput(stdin, onInterrupt)
+
+    // when
+    stdin.emit("data", "\u001b[A")
+    restore()
+
+    // then
+    expect(onInterrupt).not.toHaveBeenCalled()
+  })
+})

src/cli/run/stdin-suppression.ts

@@ -0,0 +1,52 @@
+type StdinLike = {
+  isTTY?: boolean
+  isRaw?: boolean
+  setRawMode?: (mode: boolean) => void
+  isPaused?: () => boolean
+  resume: () => void
+  pause: () => void
+  on: (event: "data", listener: (chunk: string | Uint8Array) => void) => void
+  removeListener: (event: "data", listener: (chunk: string | Uint8Array) => void) => void
+}
+
+function includesCtrlC(chunk: string | Uint8Array): boolean {
+  const text = typeof chunk === "string" ? chunk : Buffer.from(chunk).toString("utf8")
+  return text.includes("\u0003")
+}
+
+export function suppressRunInput(
+  stdin: StdinLike = process.stdin,
+  onInterrupt: () => void = () => {
+    process.kill(process.pid, "SIGINT")
+  }
+): () => void {
+  if (!stdin.isTTY) {
+    return () => {}
+  }
+
+  const wasRaw = stdin.isRaw === true
+  const wasPaused = stdin.isPaused?.() ?? false
+  const canSetRawMode = typeof stdin.setRawMode === "function"
+
+  const onData = (chunk: string | Uint8Array) => {
+    if (includesCtrlC(chunk)) {
+      onInterrupt()
+    }
+  }
+
+  if (canSetRawMode) {
+    stdin.setRawMode!(true)
+  }
+  stdin.on("data", onData)
+  stdin.resume()
+
+  return () => {
+    stdin.removeListener("data", onData)
+    if (canSetRawMode) {
+      stdin.setRawMode!(wasRaw)
+    }
+    if (wasPaused) {
+      stdin.pause()
+    }
+  }
+}

src/features/tmux-subagent/decision-engine.test.ts

@@ -258,6 +258,100 @@ describe("decideSpawnActions", () => {
       expect(result.actions[0].type).toBe("spawn")
     })
 
+    it("returns canSpawn=true when 0 agent panes exist and mainPane occupies full window width", () => {
+      // given - tmux reports mainPane.width === windowWidth when no splits exist
+      // agentAreaWidth = max(0, 252 - 252 - 1) = 0, which is < minPaneWidth
+      // but with 0 agent panes, the early return should be skipped
+      const windowWidth = 252
+      const windowHeight = 56
+      const state: WindowState = {
+        windowWidth,
+        windowHeight,
+        mainPane: { paneId: "%0", width: windowWidth, height: windowHeight, left: 0, top: 0, title: "main", isActive: true },
+        agentPanes: [],
+      }
+
+      // when
+      const result = decideSpawnActions(state, "ses1", "test", defaultConfig, [])
+
+      // then - should NOT be blocked by agentAreaWidth check
+      expect(result.canSpawn).toBe(true)
+      expect(result.actions.length).toBe(1)
+      expect(result.actions[0].type).toBe("spawn")
+    })
+
+    it("returns canSpawn=false when 0 agent panes and window genuinely too narrow to split", () => {
+      // given - window so narrow that even splitting mainPane wouldn't work
+      // canSplitPane requires width >= 2*minPaneWidth + DIVIDER_SIZE = 2*40+1 = 81
+      const windowWidth = 70
+      const windowHeight = 56
+      const state: WindowState = {
+        windowWidth,
+        windowHeight,
+        mainPane: { paneId: "%0", width: windowWidth, height: windowHeight, left: 0, top: 0, title: "main", isActive: true },
+        agentPanes: [],
+      }
+
+      // when
+      const result = decideSpawnActions(state, "ses1", "test", defaultConfig, [])
+
+      // then - should fail because mainPane itself is too small to split
+      expect(result.canSpawn).toBe(false)
+      expect(result.reason).toContain("too small")
+    })
+
+    it("returns canSpawn=false when agent panes exist but agent area too small", () => {
+      // given - 1 agent pane exists, but agent area is below minPaneWidth
+      // this verifies the early return still works for currentCount > 0
+      const state: WindowState = {
+        windowWidth: 180,
+        windowHeight: 44,
+        mainPane: { paneId: "%0", width: 160, height: 44, left: 0, top: 0, title: "main", isActive: true },
+        agentPanes: [{ paneId: "%1", width: 19, height: 44, left: 161, top: 0, title: "agent-0", isActive: false }],
+      }
+
+      // when
+      const result = decideSpawnActions(state, "ses1", "test", defaultConfig, [])
+
+      // then - agent area = max(0, 180-160-1) = 19, which is < agentPaneWidth(40)
+      expect(result.canSpawn).toBe(false)
+      expect(result.reason).toContain("too small")
+    })
+
+    it("spawns at exact minimum splittable width with 0 agent panes", () => {
+      // given - canSplitPane requires width >= 2*agentPaneWidth + DIVIDER_SIZE = 2*40+1 = 81
+      const exactThreshold = 2 * defaultConfig.agentPaneWidth + 1
+      const state: WindowState = {
+        windowWidth: exactThreshold,
+        windowHeight: 56,
+        mainPane: { paneId: "%0", width: exactThreshold, height: 56, left: 0, top: 0, title: "main", isActive: true },
+        agentPanes: [],
+      }
+
+      // when
+      const result = decideSpawnActions(state, "ses1", "test", defaultConfig, [])
+
+      // then - exactly at threshold should succeed
+      expect(result.canSpawn).toBe(true)
+    })
+
+    it("rejects spawn 1 pixel below minimum splittable width with 0 agent panes", () => {
+      // given - 1 below exact threshold
+      const belowThreshold = 2 * defaultConfig.agentPaneWidth
+      const state: WindowState = {
+        windowWidth: belowThreshold,
+        windowHeight: 56,
+        mainPane: { paneId: "%0", width: belowThreshold, height: 56, left: 0, top: 0, title: "main", isActive: true },
+        agentPanes: [],
+      }
+
+      // when
+      const result = decideSpawnActions(state, "ses1", "test", defaultConfig, [])
+
+      // then - 1 below threshold should fail
+      expect(result.canSpawn).toBe(false)
+    })
+
     it("replaces oldest pane when existing panes are too small to split", () => {
       // given - existing pane is below minimum splittable size
       const state = createWindowState(220, 30, [

src/features/tmux-subagent/spawn-action-decider.ts

@@ -32,7 +32,7 @@ export function decideSpawnActions(
 	)
 	const currentCount = state.agentPanes.length
 
-	if (agentAreaWidth < minPaneWidth) {
+	if (agentAreaWidth < minPaneWidth && currentCount > 0) {
 		return {
 			canSpawn: false,
 			actions: [],