Merge pull request #1905 from code-yeongyu/fix/tmux-split-stability

fix: stabilize tmux split and session readiness handling

src/features/tmux-subagent/action-executor-core.ts

@@ -22,9 +22,17 @@ export interface ActionExecutorDeps {
 	enforceMainPaneWidth: typeof enforceMainPaneWidth
 }
 
-async function enforceMainPane(windowState: WindowState, deps: ActionExecutorDeps): Promise<void> {
+async function enforceMainPane(
+	windowState: WindowState,
+	config: TmuxConfig,
+	deps: ActionExecutorDeps,
+): Promise<void> {
 	if (!windowState.mainPane) return
-	await deps.enforceMainPaneWidth(windowState.mainPane.paneId, windowState.windowWidth)
+	await deps.enforceMainPaneWidth(
+		windowState.mainPane.paneId,
+		windowState.windowWidth,
+		config.main_pane_size,
+	)
 }
 
 export async function executeActionWithDeps(
@@ -35,7 +43,7 @@ export async function executeActionWithDeps(
 	if (action.type === "close") {
 		const success = await deps.closeTmuxPane(action.paneId)
 		if (success) {
-			await enforceMainPane(ctx.windowState, deps)
+			await enforceMainPane(ctx.windowState, ctx.config, deps)
 		}
 		return { success }
 	}
@@ -65,7 +73,7 @@ export async function executeActionWithDeps(
 
 	if (result.success) {
 		await deps.applyLayout(ctx.config.layout, ctx.config.main_pane_size)
-		await enforceMainPane(ctx.windowState, deps)
+		await enforceMainPane(ctx.windowState, ctx.config, deps)
 	}
 
 	return {

src/features/tmux-subagent/action-executor.test.ts

@@ -86,6 +86,7 @@ describe("executeAction", () => {
 		expect(mockApplyLayout).toHaveBeenCalledTimes(1)
 		expect(mockApplyLayout).toHaveBeenCalledWith("main-horizontal", 55)
 		expect(mockEnforceMainPaneWidth).toHaveBeenCalledTimes(1)
+		expect(mockEnforceMainPaneWidth).toHaveBeenCalledWith("%0", 220, 55)
 	})
 
 	test("does not apply layout when spawn fails", async () => {

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

@@ -228,7 +228,7 @@ describe("decideSpawnActions", () => {
       expect(result.actions[0].type).toBe("spawn")
     })
 
-    it("closes oldest pane when existing panes are too small to split", () => {
+    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, [
         { paneId: "%1", width: 50, height: 15, left: 110, top: 0 },
@@ -242,9 +242,8 @@ describe("decideSpawnActions", () => {
 
       // then
       expect(result.canSpawn).toBe(true)
-      expect(result.actions.length).toBe(2)
-      expect(result.actions[0].type).toBe("close")
-      expect(result.actions[1].type).toBe("spawn")
+      expect(result.actions.length).toBe(1)
+      expect(result.actions[0].type).toBe("replace")
     })
 
     it("can spawn when existing pane is large enough to split", () => {
@@ -394,4 +393,27 @@ describe("decideSpawnActions with custom agentPaneWidth", () => {
     expect(defaultResult.canSpawn).toBe(false)
     expect(customResult.canSpawn).toBe(true)
   })
+
+  it("#given custom agentPaneWidth and splittable existing pane #when deciding spawn #then uses spawn without eviction", () => {
+    //#given
+    const customConfig: CapacityConfig = { mainPaneMinWidth: 120, agentPaneWidth: 40 }
+    const state = createWindowState(220, 44, [
+      { paneId: "%1", width: 90, height: 30, left: 110, top: 0 },
+    ])
+    const mappings: SessionMapping[] = [
+      { sessionId: "old-ses", paneId: "%1", createdAt: new Date("2024-01-01") },
+    ]
+
+    //#when
+    const result = decideSpawnActions(state, "ses1", "test", customConfig, mappings)
+
+    //#then
+    expect(result.canSpawn).toBe(true)
+    expect(result.actions.length).toBe(1)
+    expect(result.actions[0].type).toBe("spawn")
+    if (result.actions[0].type === "spawn") {
+      expect(result.actions[0].targetPaneId).toBe("%1")
+      expect(result.actions[0].splitDirection).toBe("-h")
+    }
+  })
 })

src/features/tmux-subagent/manager.test.ts

@@ -434,6 +434,53 @@ describe('TmuxSessionManager', () => {
   })
 
   describe('onSessionDeleted', () => {
+    test('does not track session when readiness timed out', async () => {
+      // given
+      mockIsInsideTmux.mockReturnValue(true)
+      let stateCallCount = 0
+      mockQueryWindowState.mockImplementation(async () => {
+        stateCallCount++
+        if (stateCallCount === 1) {
+          return createWindowState()
+        }
+        return createWindowState({
+          agentPanes: [
+            {
+              paneId: '%mock',
+              width: 40,
+              height: 44,
+              left: 100,
+              top: 0,
+              title: 'omo-subagent-Timeout Task',
+              isActive: false,
+            },
+          ],
+        })
+      })
+
+      const { TmuxSessionManager } = await import('./manager')
+      const ctx = createMockContext({ sessionStatusResult: { data: {} } })
+      const config: TmuxConfig = {
+        enabled: true,
+        layout: 'main-vertical',
+        main_pane_size: 60,
+        main_pane_min_width: 80,
+        agent_pane_min_width: 40,
+      }
+      const manager = new TmuxSessionManager(ctx, config, mockTmuxDeps)
+
+      await manager.onSessionCreated(
+        createSessionCreatedEvent('ses_timeout', 'ses_parent', 'Timeout Task')
+      )
+      mockExecuteAction.mockClear()
+
+      // when
+      await manager.onSessionDeleted({ sessionID: 'ses_timeout' })
+
+      // then
+      expect(mockExecuteAction).toHaveBeenCalledTimes(0)
+    })
+
     test('closes pane when tracked session is deleted', async () => {
       // given
       mockIsInsideTmux.mockReturnValue(true)
@@ -521,8 +568,13 @@ describe('TmuxSessionManager', () => {
       mockIsInsideTmux.mockReturnValue(true)
 
       let callCount = 0
-      mockExecuteActions.mockImplementation(async () => {
+      mockExecuteActions.mockImplementation(async (actions) => {
         callCount++
+        for (const action of actions) {
+          if (action.type === 'spawn') {
+            trackedSessions.add(action.sessionId)
+          }
+        }
         return {
           success: true,
           spawnedPaneId: `%${callCount}`,

src/features/tmux-subagent/manager.ts

@@ -213,10 +213,17 @@ export class TmuxSessionManager {
         const sessionReady = await this.waitForSessionReady(sessionId)
         
         if (!sessionReady) {
-          log("[tmux-session-manager] session not ready after timeout, tracking anyway", {
+          log("[tmux-session-manager] session not ready after timeout, closing spawned pane", {
             sessionId,
             paneId: result.spawnedPaneId,
           })
+
+          await executeAction(
+            { type: "close", paneId: result.spawnedPaneId, sessionId },
+            { config: this.tmuxConfig, serverUrl: this.serverUrl, windowState: state }
+          )
+
+          return
         }
         
         const now = Date.now()

src/features/tmux-subagent/pane-split-availability.ts

@@ -57,11 +57,21 @@ export function canSplitPane(
 }
 
 export function canSplitPaneAnyDirection(pane: TmuxPaneInfo): boolean {
-	return pane.width >= MIN_SPLIT_WIDTH || pane.height >= MIN_SPLIT_HEIGHT
+	return canSplitPaneAnyDirectionWithMinWidth(pane, MIN_PANE_WIDTH)
 }
 
-export function getBestSplitDirection(pane: TmuxPaneInfo): SplitDirection | null {
-	const canH = pane.width >= MIN_SPLIT_WIDTH
+export function canSplitPaneAnyDirectionWithMinWidth(
+	pane: TmuxPaneInfo,
+	minPaneWidth: number = MIN_PANE_WIDTH,
+): boolean {
+	return pane.width >= minSplitWidthFor(minPaneWidth) || pane.height >= MIN_SPLIT_HEIGHT
+}
+
+export function getBestSplitDirection(
+	pane: TmuxPaneInfo,
+	minPaneWidth: number = MIN_PANE_WIDTH,
+): SplitDirection | null {
+	const canH = pane.width >= minSplitWidthFor(minPaneWidth)
 	const canV = pane.height >= MIN_SPLIT_HEIGHT
 
 	if (!canH && !canV) return null

src/features/tmux-subagent/session-created-handler.ts

@@ -135,10 +135,21 @@ export async function handleSessionCreated(
 
     const sessionReady = await deps.waitForSessionReady(sessionId)
     if (!sessionReady) {
-      log("[tmux-session-manager] session not ready after timeout, tracking anyway", {
+      log("[tmux-session-manager] session not ready after timeout, closing spawned pane", {
         sessionId,
         paneId: result.spawnedPaneId,
       })
+
+      await executeActions(
+        [{ type: "close", paneId: result.spawnedPaneId, sessionId }],
+        {
+          config: deps.tmuxConfig,
+          serverUrl: deps.serverUrl,
+          windowState: state,
+        },
+      )
+
+      return
     }
 
     const now = Date.now()

src/features/tmux-subagent/session-spawner.ts

@@ -129,10 +129,21 @@ export class SessionSpawner {
         const sessionReady = await this.waitForSessionReady(sessionId)
         
         if (!sessionReady) {
-          log("[tmux-session-manager] session not ready after timeout, tracking anyway", {
+          log("[tmux-session-manager] session not ready after timeout, closing spawned pane", {
             sessionId,
             paneId: result.spawnedPaneId,
           })
+
+          await executeActions(
+            [{ type: "close", paneId: result.spawnedPaneId, sessionId }],
+            {
+              config: this.tmuxConfig,
+              serverUrl: this.serverUrl,
+              windowState: state,
+            },
+          )
+
+          return
         }
         
         const now = Date.now()

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

@@ -62,7 +62,7 @@ export function decideSpawnActions(
 	}
 
 	if (isSplittableAtCount(agentAreaWidth, currentCount, minPaneWidth)) {
-		const spawnTarget = findSpawnTarget(state)
+		const spawnTarget = findSpawnTarget(state, minPaneWidth)
 		if (spawnTarget) {
 			return {
 				canSpawn: true,
@@ -85,19 +85,14 @@ export function decideSpawnActions(
 			canSpawn: true,
 			actions: [
 				{
-					type: "close",
+					type: "replace",
 					paneId: oldestPane.paneId,
-					sessionId: oldestMapping?.sessionId || "",
-				},
-				{
-					type: "spawn",
-					sessionId,
+					oldSessionId: oldestMapping?.sessionId || "",
+					newSessionId: sessionId,
 					description,
-					targetPaneId: state.mainPane.paneId,
-					splitDirection: "-h",
 				},
 			],
-			reason: "closed 1 pane to make room for split",
+			reason: "replaced oldest pane to avoid split churn",
 		}
 	}
 

src/features/tmux-subagent/spawn-target-finder.ts

@@ -2,6 +2,7 @@ import type { SplitDirection, TmuxPaneInfo, WindowState } from "./types"
 import { MAIN_PANE_RATIO } from "./tmux-grid-constants"
 import { computeGridPlan, mapPaneToSlot } from "./grid-planning"
 import { canSplitPane, getBestSplitDirection } from "./pane-split-availability"
+import { MIN_PANE_WIDTH } from "./types"
 
 export interface SpawnTarget {
 	targetPaneId: string
@@ -37,6 +38,7 @@ function findFirstEmptySlot(
 
 function findSplittableTarget(
 	state: WindowState,
+	minPaneWidth: number,
 	_preferredDirection?: SplitDirection,
 ): SpawnTarget | null {
 	if (!state.mainPane) return null
@@ -44,7 +46,7 @@ function findSplittableTarget(
 
 	if (existingCount === 0) {
 		const virtualMainPane: TmuxPaneInfo = { ...state.mainPane, width: state.windowWidth }
-		if (canSplitPane(virtualMainPane, "-h")) {
+		if (canSplitPane(virtualMainPane, "-h", minPaneWidth)) {
 			return { targetPaneId: state.mainPane.paneId, splitDirection: "-h" }
 		}
 		return null
@@ -56,17 +58,17 @@ function findSplittableTarget(
 	const targetSlot = findFirstEmptySlot(occupancy, plan)
 
 	const leftPane = occupancy.get(`${targetSlot.row}:${targetSlot.col - 1}`)
-	if (leftPane && canSplitPane(leftPane, "-h")) {
+	if (leftPane && canSplitPane(leftPane, "-h", minPaneWidth)) {
 		return { targetPaneId: leftPane.paneId, splitDirection: "-h" }
 	}
 
 	const abovePane = occupancy.get(`${targetSlot.row - 1}:${targetSlot.col}`)
-	if (abovePane && canSplitPane(abovePane, "-v")) {
+	if (abovePane && canSplitPane(abovePane, "-v", minPaneWidth)) {
 		return { targetPaneId: abovePane.paneId, splitDirection: "-v" }
 	}
 
 	const splittablePanes = state.agentPanes
-		.map((pane) => ({ pane, direction: getBestSplitDirection(pane) }))
+		.map((pane) => ({ pane, direction: getBestSplitDirection(pane, minPaneWidth) }))
 		.filter(
 			(item): item is { pane: TmuxPaneInfo; direction: SplitDirection } =>
 				item.direction !== null,
@@ -81,6 +83,9 @@ function findSplittableTarget(
 	return null
 }
 
-export function findSpawnTarget(state: WindowState): SpawnTarget | null {
-	return findSplittableTarget(state)
+export function findSpawnTarget(
+	state: WindowState,
+	minPaneWidth: number = MIN_PANE_WIDTH,
+): SpawnTarget | null {
+	return findSplittableTarget(state, minPaneWidth)
 }

src/shared/tmux/tmux-utils/layout.ts

@@ -29,13 +29,15 @@ export async function applyLayout(
 export async function enforceMainPaneWidth(
 	mainPaneId: string,
 	windowWidth: number,
+	mainPaneSize: number,
 ): Promise<void> {
 	const { log } = await import("../../logger")
 	const tmux = await getTmuxPath()
 	if (!tmux) return
 
 	const dividerWidth = 1
-	const mainWidth = Math.floor((windowWidth - dividerWidth) / 2)
+	const boundedMainPaneSize = Math.max(20, Math.min(80, mainPaneSize))
+	const mainWidth = Math.floor(((windowWidth - dividerWidth) * boundedMainPaneSize) / 100)
 
 	const proc = spawn([tmux, "resize-pane", "-t", mainPaneId, "-x", String(mainWidth)], {
 		stdout: "ignore",
@@ -47,5 +49,6 @@ export async function enforceMainPaneWidth(
 		mainPaneId,
 		mainWidth,
 		windowWidth,
+		mainPaneSize: boundedMainPaneSize,
 	})
 }