From 6209412f2cd7c9c7383718e4d74ed797ee824dfe Mon Sep 17 00:00:00 2001
From: Neil <neil@stably.ai>
Date: Sun, 5 Jul 2026 15:28:22 -0700
Subject: [PATCH] fix(daemon): self-heal write routing for undiscovered legacy
 sessions
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DaemonPtyRouter fans out reads (onData/hasPty/listProcesses) across every
adapter, but routes writes and resizes via a sessionAdapters map that is
populated only by the one-shot discoverLegacySessions()/reconcile/spawn boot
passes. When a surviving previous-protocol daemon owns a session that boot
discovery missed (e.g. a Windows named-pipe/startup-order race, widened by the
.perf startup reordering), adapterFor() fell back to `this.current` — so output
kept streaming (reads fan out) while every keystroke was silently dispatched to
the wrong daemon and dropped. Symptom: adopted terminals stream live output but
accept no input after a protocol-bumping update.

Make adapterFor() self-heal: on a routing-map miss, ask each adapter whether it
owns the pty (synchronous Set lookup), cache the winner, and route there;
current-first precedence keeps the safe default. This mirrors the self-healing
providerFor() already used by DegradedDaemonPtyProvider.

Adds regression tests covering the undiscovered-legacy-session route and the
no-owner fallback.
---
 src/main/daemon/daemon-pty-router.test.ts | 28 +++++++++++++++++++++++
 src/main/daemon/daemon-pty-router.ts      | 15 +++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/main/daemon/daemon-pty-router.test.ts b/src/main/daemon/daemon-pty-router.test.ts
index 47d44aa807c..3522811b30e 100644
--- a/src/main/daemon/daemon-pty-router.test.ts
+++ b/src/main/daemon/daemon-pty-router.test.ts
@@ -118,6 +118,34 @@ describe('DaemonPtyRouter', () => {
     expect(current.write).toHaveBeenCalledWith(fresh.id, 'new\n')
   })
 
+  it('routes an undiscovered legacy session to its owning daemon, not current', () => {
+    // Reproduces the frozen-input bug: the old daemon still owns the session
+    // (hasPty true, output streaming), but the one-shot discoverLegacySessions()
+    // boot pass never mapped it — so the routing map is empty for this id.
+    const current = createAdapter('current')
+    const legacy = createAdapter('legacy', ['orphan-session'])
+    const router = new DaemonPtyRouter({ current, legacy: [legacy] })
+
+    // Deliberately NO discoverLegacySessions() / reconcile / spawn call.
+    router.write('orphan-session', 'input\n')
+    router.resize('orphan-session', 80, 24)
+
+    expect(legacy.write).toHaveBeenCalledWith('orphan-session', 'input\n')
+    expect(legacy.resize).toHaveBeenCalledWith('orphan-session', 80, 24)
+    expect(current.write).not.toHaveBeenCalled()
+  })
+
+  it('falls back to the current adapter when no adapter owns the session', () => {
+    const current = createAdapter('current')
+    const legacy = createAdapter('legacy')
+    const router = new DaemonPtyRouter({ current, legacy: [legacy] })
+
+    router.write('unknown-session', 'input\n')
+
+    expect(current.write).toHaveBeenCalledWith('unknown-session', 'input\n')
+    expect(legacy.write).not.toHaveBeenCalled()
+  })
+
   it('drops a legacy mapping after the routed session exits', async () => {
     const current = createAdapter('current')
     const legacy = createAdapter('legacy', ['legacy-session'])
diff --git a/src/main/daemon/daemon-pty-router.ts b/src/main/daemon/daemon-pty-router.ts
index 1f80f770cd9..a1d6a0344cb 100644
--- a/src/main/daemon/daemon-pty-router.ts
+++ b/src/main/daemon/daemon-pty-router.ts
@@ -250,7 +250,20 @@ export class DaemonPtyRouter implements IPtyProvider {
   }
 
   private adapterFor(sessionId: string): DaemonPtyAdapter {
-    return this.sessionAdapters.get(sessionId) ?? this.current
+    const routed = this.sessionAdapters.get(sessionId)
+    if (routed) {
+      return routed
+    }
+    // Why: reads fan out across all adapters, but this routing map is filled only
+    // by one-shot boot discovery. A legacy session it missed had its writes silently
+    // dropped onto `current`; self-heal by asking who actually owns the pty, then cache.
+    for (const adapter of this.allAdapters()) {
+      if (adapter.hasPty(sessionId)) {
+        this.sessionAdapters.set(sessionId, adapter)
+        return adapter
+      }
+    }
+    return this.current
   }
 
   private allAdapters(): DaemonPtyAdapter[] {