fix: hot-rebind server when Tailscale becomes available by jcanizalez · Pull Request #102 · jcanizalez/vibegrid

jcanizalez · 2026-03-26T03:19:28Z

Summary

Adds a server-rebind module that re-listens the HTTP server on 0.0.0.0 when Tailscale becomes available after app startup
Triggers rebind automatically on config change (toggling Remote Access) and on refresh (tailscale:status RPC)
Both Electron and web clients auto-reconnect after the brief rebind interruption

Test plan

Start app with Tailscale disabled, enable Tailscale, toggle "Enable Remote Access" → verify the app is reachable on the Tailscale IP
With Remote Access already enabled, restart Tailscale, press Refresh → verify rebind happens
Disable Remote Access → verify server rebinds back to 127.0.0.1
Verify Electron client reconnects after rebind without manual intervention

- Extend AgentPicker with allowNone prop for optional agent selection - Add agent picker to AddTaskDialog toolbar (between project and branch) - Make agent field editable in TaskDetailPanel with auto-save - Wire assignedAgent into create/update payloads - Add 8 tests for AgentPicker nullable behavior Closes #95

The server binds its listen address at startup. If Tailscale was not running at launch time, the server stays on 127.0.0.1 even after Tailscale connects — making the app unreachable from remote devices. Add a server-rebind module that re-listens on 0.0.0.0 when networkAccessEnabled is toggled or the refresh button is pressed.

Copilot

Pull request overview

Adds infrastructure to hot-rebind the embedded HTTP server when Tailscale/network access becomes available after startup, and updates UI to support nullable agent assignment via AgentPicker.

Changes:

Introduces packages/server/src/server-rebind.ts and wires it into server startup, config changes, and tailscale:status RPC.
Updates AgentPicker to support an “Unassigned/None” state (allowNone, nullable currentAgent/onChange) and adopts it in task create/edit surfaces.
Adds Vitest coverage for the new nullable AgentPicker behavior.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/agent-picker-nullable.test.tsx	Adds tests for `AgentPicker` when `allowNone` enables a nullable selection.
src/renderer/components/workflow-editor/panels/LaunchAgentConfigForm.tsx	Adjusts `AgentPicker` usage to accommodate nullable callback typing.
src/renderer/components/TaskDetailPanel.tsx	Replaces static agent display with editable `AgentPicker` (nullable assignment).
src/renderer/components/AgentPicker.tsx	Adds `allowNone` + nullable agent support and UI for “Unassigned/None”.
src/renderer/components/AddTaskDialog.tsx	Adds agent assignment to task create/edit via `AgentPicker`.
packages/server/src/server-rebind.ts	New module to rebind server host between `127.0.0.1` and `0.0.0.0` based on config + Tailscale state.
packages/server/src/register-methods.ts	Makes `tailscale:status` async and triggers rebind checks on refresh.
packages/server/src/index.ts	Initializes rebind module and triggers rebind checks on config change.

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Copilot · 2026-03-26T03:24:16Z

packages/server/src/server-rebind.ts

+      server.listen(boundPort, desiredHost, () => resolve())
+      server.once('error', reject)


In the listen() promise, server.once('error', reject) is never removed on a successful bind. If rebind happens multiple times without errors, these one-time listeners will accumulate and can trigger MaxListeners warnings / leaks. Attach an onError handler and remove it in the listen callback (or use a helper that races once(server,'error') vs once(server,'listening')).

Suggested change

server.listen(boundPort, desiredHost, () => resolve())

server.once('error', reject)

const onError = (err: unknown) => {

server.removeListener('listening', onListening)

reject(err)

}

const onListening = () => {

server.removeListener('error', onError)

resolve()

}

server.once('error', onError)

server.listen(boundPort, desiredHost, onListening)

Fixed in 9cb59d7 — paired onError/onListening handlers that remove each other on resolution.

Copilot · 2026-03-26T03:24:16Z

src/renderer/components/TaskDetailPanel.tsx

+          <div className="flex items-center gap-2 text-[12px]">
+            <span className="text-gray-600 w-20 shrink-0">Agent</span>
+            <AgentPicker
+              currentAgent={formAssignedAgent}
+              onChange={setFormAssignedAgent}
+              installStatus={agentInstallStatus}
+              allowNone
+            />
+          </div>


The PR title/description focus on hot-rebinding the server when Tailscale becomes available, but this change introduces a new task "Agent" assignment UI (via AgentPicker with allowNone) which isn't mentioned. Please either update the PR description/test plan to cover the task-assignment UI change or split these UI changes into a separate PR to keep scope clear.

The agent-picker changes are from a prior commit on this branch (163f4c7) — not part of this fix. Will land separately.

Copilot · 2026-03-26T03:24:16Z

packages/server/src/server-rebind.ts

+/**
+ * Check if the server needs to rebind based on current config + Tailscale state.
+ * Binds to 0.0.0.0 when networkAccessEnabled AND Tailscale is running, else 127.0.0.1.
+ */
+export async function checkAndRebind(): Promise<void> {
+  if (!httpServer) return
+
+  const config = configManager.loadConfig()
+  let desiredHost = '127.0.0.1'
+
+  if (config.defaults.networkAccessEnabled) {
+    try {
+      const tsStatus = await getTailscaleStatus()
+      if (tsStatus.running) {
+        desiredHost = '0.0.0.0'
+      }
+    } catch {
+      // Tailscale check failed, stay on localhost
+    }
+  }


packages/server/src/server-rebind.ts introduces new host-selection and rebind behavior, but there are no tests covering it. Since server code is already covered by Vitest, adding focused unit tests (e.g., desiredHost selection based on config + mocked Tailscale status, and that close()/listen() are invoked when the host changes) would help prevent regressions.

Agreed this is worth covering. Will add in a follow-up.

Added in 304253a — 9 tests covering: no-op cases, rebind to 0.0.0.0 / back to 127.0.0.1, Tailscale failure handling, listen error recovery, concurrent call serialization, and port preservation.

Copilot · 2026-03-26T03:24:16Z

packages/server/src/server-rebind.ts

+  try {
+    const server = httpServer
+    if (typeof server.closeAllConnections === 'function') {
+      server.closeAllConnections()
+    }
+    await new Promise<void>((resolve) => server.close(() => resolve()))
+    await new Promise<void>((resolve, reject) => {
+      server.listen(boundPort, desiredHost, () => resolve())
+      server.once('error', reject)
+    })


checkAndRebind() can be invoked from multiple places (config change handler and the tailscale:status RPC). As written, concurrent calls can interleave close()/listen() on the same httpServer, which can leave the server closed or in an error state. Consider serializing rebinding with a module-level mutex/in-flight promise so only one close→listen sequence can run at a time (and later calls either await or no-op).

Fixed in 9cb59d7 — added a rebindInFlight mutex so concurrent calls await the in-progress rebind instead of interleaving.

- Add mutex so concurrent checkAndRebind() calls don't interleave close/listen on the same server - Remove error listener on successful bind to prevent accumulation

Covers: no-op cases, rebind to 0.0.0.0 / back to 127.0.0.1, Tailscale failure handling, listen error recovery, concurrent call serialization, and port preservation.

jcanizalez added 2 commits March 25, 2026 20:29

Copilot AI review requested due to automatic review settings March 26, 2026 03:19

Copilot started reviewing on behalf of jcanizalez March 26, 2026 03:19 View session

Copilot AI reviewed Mar 26, 2026

View reviewed changes

jcanizalez added 2 commits March 25, 2026 21:48

fix: address review — serialize rebind and clean up listeners

9cb59d7

- Add mutex so concurrent checkAndRebind() calls don't interleave close/listen on the same server - Remove error listener on successful bind to prevent accumulation

test: add unit tests for server-rebind module

304253a

Covers: no-op cases, rebind to 0.0.0.0 / back to 127.0.0.1, Tailscale failure handling, listen error recovery, concurrent call serialization, and port preservation.

jcanizalez merged commit 5086853 into main Mar 26, 2026
1 check passed

jcanizalez deleted the feat/agent-picker-tasks-worktree-67544611 branch March 26, 2026 15:19

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fix: hot-rebind server when Tailscale becomes available#102

fix: hot-rebind server when Tailscale becomes available#102
jcanizalez merged 4 commits intomainfrom
feat/agent-picker-tasks-worktree-67544611

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		server.listen(boundPort, desiredHost, () => resolve())
		server.once('error', reject)

-      server.listen(boundPort, desiredHost, () => resolve())
-      server.once('error', reject)
+      const onError = (err: unknown) => {
+        server.removeListener('listening', onListening)
+        reject(err)
+      }
+      const onListening = () => {
+        server.removeListener('error', onError)
+        resolve()
+      }
+      server.once('error', onError)
+      server.listen(boundPort, desiredHost, onListening)

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jcanizalez commented Mar 26, 2026

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