merge(dev): resolve latest sync-task conflict for delegated fallback PR

Sync the PR branch with the latest dev branch and resolve the remaining conflict in sync-task.test.ts while preserving both the new upstream poll-recovery coverage and this branch's delegated bootstrap cleanup and isolation coverage. Re-verified the affected delegated fallback suites and typecheck after the merge resolution.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/migrate-legacy-plugin-entry.ts

@@ -54,7 +54,7 @@ export function migrateLegacyPluginEntry(configPath: string): boolean {
 
     const tempPath = `${configPath}.tmp`
     writeFileSync(tempPath, updated, "utf-8")
-    const tempFileDescriptor = openSync(tempPath, "r")
+    const tempFileDescriptor = openSync(tempPath, "r+")
     try {
       fsyncSync(tempFileDescriptor)
     } finally {

src/shared/model-settings-compatibility.test.ts

@@ -615,6 +615,18 @@ describe("resolveCompatibleModelSettings", () => {
     expect(result.changes).toEqual([])
   })
 
+  test("#given desired.maxTokens is 0 #then maxTokens is dropped", () => {
+    const result = resolveCompatibleModelSettings({
+      providerID: "openai",
+      modelID: "gpt-5.4",
+      desired: { maxTokens: 0 },
+      capabilities: { maxOutputTokens: 128_000 },
+    })
+
+    expect(result.maxTokens).toBeUndefined()
+    expect(result.changes).toEqual([])
+  })
+
   // Passthrough: undefined desired values produce no changes
   test("no-op when desired settings are empty", () => {
     const result = resolveCompatibleModelSettings({

src/shared/model-settings-compatibility.ts

@@ -175,6 +175,10 @@ export function resolveCompatibleModelSettings(
   }
 
   let maxTokens = input.desired.maxTokens
+  if (maxTokens !== undefined && maxTokens <= 0) {
+    maxTokens = undefined
+  }
+
   if (
     maxTokens !== undefined &&
     input.capabilities?.maxOutputTokens !== undefined &&

src/shared/tmux/cmux-detect.ts

@@ -0,0 +1,11 @@
+/**
+ * Detect whether we are running inside cmux (cmux omo).
+ * When cmux-omo sets up the environment it injects a tmux shim and sets
+ * CMUX_SOCKET_PATH / TMUX. If detected, redirect tmux commands to
+ * `cmux __tmux-compat` so they become native cmux splits instead of
+ * failing because there is no real tmux server running.
+ */
+export function isCmuxCompatEnvironment(): boolean {
+	return Boolean(process.env.CMUX_SOCKET_PATH) ||
+		process.env.TMUX?.includes("cmuxterm") === true
+}

src/shared/tmux/index.ts

@@ -1,4 +1,5 @@
 export * from "./types"
 export * from "./constants"
+export * from "./cmux-detect"
 export * from "./runner"
 export * from "./tmux-utils"

src/shared/tmux/runner.test.ts

@@ -1,6 +1,6 @@
 /// <reference types="bun-types" />
 
-import { afterAll, describe, expect, test } from "bun:test"
+import { afterAll, beforeEach, describe, expect, test } from "bun:test"
 import { randomUUID } from "node:crypto"
 import fs from "node:fs/promises"
 import os from "node:os"
@@ -9,6 +9,9 @@ import path from "node:path"
 import { runTmuxCommand } from "./runner"
 
 const temporaryDirectories: string[] = []
+const originalCmuxSocketPath = process.env.CMUX_SOCKET_PATH
+const originalTmux = process.env.TMUX
+const originalPath = process.env.PATH
 
 async function createTemporaryDirectory(): Promise<string> {
 	const directoryPath = await fs.mkdtemp(path.join(os.tmpdir(), "tmux-runner-"))
@@ -21,7 +24,39 @@ async function readInvocationCount(counterFilePath: string): Promise<number> {
 	return Number.parseInt(count, 10)
 }
 
+async function createFakeCmux(directoryPath: string, argsFilePath: string): Promise<string> {
+	const cmuxPath = path.join(directoryPath, "cmux")
+	const script = [
+		"#!/bin/sh",
+		"printf '%s\\n' \"$@\" > \"$1.args\"",
+		"printf '%s\\n' '%42'",
+	].join("\n")
+	await fs.writeFile(cmuxPath, script.replace("$1.args", argsFilePath), "utf8")
+	await fs.chmod(cmuxPath, 0o755)
+	return cmuxPath
+}
+
+beforeEach(() => {
+	delete process.env.CMUX_SOCKET_PATH
+	delete process.env.TMUX
+	process.env.PATH = originalPath
+})
+
 afterAll(async () => {
+	if (originalCmuxSocketPath === undefined) {
+		delete process.env.CMUX_SOCKET_PATH
+	} else {
+		process.env.CMUX_SOCKET_PATH = originalCmuxSocketPath
+	}
+
+	if (originalTmux === undefined) {
+		delete process.env.TMUX
+	} else {
+		process.env.TMUX = originalTmux
+	}
+
+	process.env.PATH = originalPath
+
 	for (const directoryPath of temporaryDirectories) {
 		await fs.rm(directoryPath, { recursive: true, force: true })
 	}
@@ -124,4 +159,26 @@ describe("runTmuxCommand", () => {
 		expect(success).toBe(true)
 		expect(output).toBe("%9")
 	})
+
+	test("#given cmux environment #when run #then delegates through cmux tmux compatibility command", async () => {
+		// given
+		const temporaryDirectory = await createTemporaryDirectory()
+		const argsFilePath = path.join(temporaryDirectory, "cmux.args")
+		const cmuxPath = await createFakeCmux(temporaryDirectory, argsFilePath)
+		process.env.CMUX_SOCKET_PATH = path.join(temporaryDirectory, "cmux.sock")
+		process.env.PATH = `${temporaryDirectory}${path.delimiter}${originalPath ?? ""}`
+
+		// when
+		const result = await runTmuxCommand(cmuxPath, ["display-message", "-p", "#{pane_id}"])
+
+		// then
+		expect(result).toEqual({
+			success: true,
+			output: "%42",
+			stdout: "%42",
+			stderr: "",
+			exitCode: 0,
+		})
+		await expect(fs.readFile(argsFilePath, "utf8")).resolves.toBe("__tmux-compat\ndisplay-message\n-p\n#{pane_id}\n")
+	})
 })

src/shared/tmux/runner.ts

@@ -1,4 +1,5 @@
 import { spawn } from "../bun-spawn-shim"
+import { isCmuxCompatEnvironment } from "./cmux-detect"
 
 type RunTmuxOptions = {
 	retry?: number
@@ -29,20 +30,14 @@ function isTerminalTmuxError(stderr: string): boolean {
 	return TERMINAL_TMUX_ERROR_PATTERN.test(stderr)
 }
 
-/**
- * Detect whether we are running inside cmux (cmux omo).
- * When cmux-omo sets up the environment it injects a tmux shim and sets
- * CMUX_SOCKET_PATH / TMUX. If detected, redirect tmux commands to
- * `cmux __tmux-compat` so they become native cmux splits instead of
- * failing because there is no real tmux server running.
- */
 function resolveTmuxExecutable(tmuxPath: string): string[] {
-	const inCmux = Boolean(process.env.CMUX_SOCKET_PATH) ||
-		process.env.TMUX?.includes("cmuxterm") === true
-	if (inCmux) {
-		return ["cmux", "__tmux-compat"]
+	if (!isCmuxCompatEnvironment()) {
+		return [tmuxPath]
 	}
-	return [tmuxPath]
+
+	const executableName = tmuxPath.split(/[\\/]/).pop()
+	const cmuxExecutable = executableName === "cmux" ? tmuxPath : "cmux"
+	return [cmuxExecutable, "__tmux-compat"]
 }
 
 async function runTmuxCommandOnce(tmuxPath: string, args: Array<string>, timeoutMs?: number): Promise<TmuxCommandResult> {

src/shared/write-file-atomically.ts

@@ -16,7 +16,7 @@ export function writeFileAtomically(
 ): void {
   const tempPath = `${filePath}.tmp`
   writeFileSync(tempPath, content, "utf-8")
-  const tempFileDescriptor = openSync(tempPath, "r")
+  const tempFileDescriptor = openSync(tempPath, "r+")
   try {
     tolerantFsyncSync(tempFileDescriptor, `writeFileAtomically:${filePath}`, deps.fsyncSync)
   } finally {

src/shared/zauc-mocks-migrate-legacy-plugin/migrate-legacy-plugin-entry.test.ts

@@ -96,6 +96,41 @@ describe("migrateLegacyPluginEntry", () => {
     })
   })
 
+  describe("#given migration writes a temp file for fsync", () => {
+    describe("#when opening the temp file descriptor", () => {
+      it("#then uses r+ mode to satisfy FlushFileBuffers requirements on Windows", async () => {
+        const configPath = join(testDir, "opencode.json")
+        writeFileSync(configPath, JSON.stringify({ plugin: ["oh-my-opencode@latest"] }, null, 2))
+
+        const fs = await import("node:fs")
+        const originalOpenSync = fs.openSync
+        const openSyncCalls: string[] = []
+
+        mock.module("node:fs", () => ({
+          ...fs,
+          openSync: (path: Parameters<typeof fs.openSync>[0], flags: Parameters<typeof fs.openSync>[1]) => {
+            openSyncCalls.push(String(flags))
+            return originalOpenSync(path, flags)
+          },
+        }))
+
+        try {
+          const { migrateLegacyPluginEntry } = await importFreshMigrationModule()
+
+          const result = migrateLegacyPluginEntry(configPath)
+
+          expect(result).toBe(true)
+          expect(openSyncCalls).toContain("r+")
+        } finally {
+          mock.module("node:fs", () => ({
+            ...fs,
+            openSync: originalOpenSync,
+          }))
+        }
+      })
+    })
+  })
+
   describe("#given opencode.json contains pinned oh-my-opencode version", () => {
     describe("#when migrating the config", () => {
       it("#then preserves the version pin", async () => {
@@ -217,4 +252,4 @@ describe("migrateLegacyPluginEntry", () => {
       })
     })
   })
-})
+})