fix: recover interactive input after resume

[angeiv]

Problem

After resuming a session via /resume, the interactive UI can stop submitting later input correctly. Text remains in the input surface instead of flowing through the active session prompt loop.

Root Cause

The first fix attempted to call runtime.session.init(), but runtime.session is an AgentSession, not the upstream InteractiveMode, so that path is effectively a no-op. The actual resume path replaces the active AgentSession and invokes the interactive mode setRebindSession callback.

Fix

Install a GLM-side interactive rebind recovery hook in runChatSession:

• preserve the upstream rebindCurrentSession() behavior after session replacement
• refresh the editor submit handler after resume/new/fork/import replacement
• restore editor focus and request a render after the rebind
• remove the previous no-op AgentSession.init() call

Verification

• pnpm test tests/runtime/chat-runtime.test.ts
• pnpm test tests/runtime/chat-runtime.test.ts tests/session/create-session.test.ts
• pnpm test
• pnpm build

[angeiv]

Review note: I do not think this PR fixes the reported resume input issue as written.

The added code calls runtime.session.init?.() after originalSwitchSession(), but in the current upstream @mariozechner/pi-coding-agent@0.70.0, AgentSessionRuntime.session is an AgentSession, not InteractiveMode. AgentSession does not expose init(), so this guard is expected to be a no-op in the actual runtime path.

The interactive layer is created separately in src/runtime/chat-runtime.ts as new InteractiveMode(runtime, ...). Upstream InteractiveMode registers runtimeHost.setRebindSession(async () => this.rebindCurrentSession()) in its constructor, and AgentSessionRuntime.switchSession() calls finishSessionReplacement(), which invokes that rebind callback. That means the real resume path should already rebind the current InteractiveMode rather than creating a new one or requiring AgentSession.init().

Suggested next step: please trace why InteractiveMode.rebindCurrentSession() / renderCurrentSessionState() / editor submit state is insufficient after resume. A regression test should prove that after switchSession(), the editor submit handler is still bound to the active interactive session. Without that, this change can pass CI while leaving the user-visible bug unchanged.

[angeiv]

Updated this PR with a real interactive-layer fix.

What changed:

• Removed the previous runtime.session.init() call because runtime.session is AgentSession, not InteractiveMode, so that path does not reliably execute.
• Added installInteractiveSessionRebindRecovery() in src/runtime/chat-runtime.ts.
• The recovery hook replaces the interactive runtime rebind callback with: upstream rebindCurrentSession(), then submit handler refresh, editor focus restore, and render request.
• Added regression coverage in tests/runtime/chat-runtime.test.ts for the recovery hook and for runChatSession installing it before starting interactive mode.

Local verification passed:

• pnpm test tests/runtime/chat-runtime.test.ts
• pnpm test tests/runtime/chat-runtime.test.ts tests/session/create-session.test.ts
• pnpm test
• pnpm build