feat(extension): make WINDOW_IDLE_TIMEOUT configurable via OPENCLI_WINDOW_IDLE_TIMEOUT env var

[xzygis]

Summary

Make the extension's automation window idle timeout configurable via the OPENCLI_WINDOW_IDLE_TIMEOUT environment variable, following the same per-command relay pattern used by OPENCLI_WINDOW_FOCUSED (#915).

Closes #1014

Problem

The extension's WINDOW_IDLE_TIMEOUT is hardcoded to 30 seconds. When opencli browser subcommands are used by AI agents, the automation window closes between commands because agents typically need 30-60+ seconds to analyze state and plan the next action.

Unlike adapter commands (which explicitly call closeWindow() per #915), opencli browser subcommands rely entirely on the idle timer for window lifecycle — making the 30s default too aggressive.

Changes

3 files, +15/-6 lines — minimal and focused:

extension/src/protocol.ts

• Add windowIdleTimeout?: number to Command interface

src/browser/daemon-client.ts

• Add windowIdleTimeout?: number to DaemonCommand interface
• Read OPENCLI_WINDOW_IDLE_TIMEOUT env var (seconds, min 5), convert to ms, attach per-command

extension/src/background.ts

• Replace hardcoded WINDOW_IDLE_TIMEOUT = 30000 with DEFAULT_WINDOW_IDLE_TIMEOUT = 600_000 (10 min)
• Use mutable windowIdleTimeout variable updated from per-command payload
• All idle timer code uses the variable instead of the constant

Design Decisions

1. Per-command relay (not stored in chrome.storage): Follows the windowFocused pattern from feat: auto-close adapter windows, add OPENCLI_WINDOW_FOCUSED, document config #915. Each command carries the timeout value, keeping the extension stateless.

2. Default raised to 10 minutes: Adapter commands already close windows immediately (feat: auto-close adapter windows, add OPENCLI_WINDOW_FOCUSED, document config #915), so the idle timer only matters for opencli browser sessions. 10 minutes gives AI agents ample time between steps.

3. Minimum 5 seconds: Prevents misconfiguration from making windows uncloseable.

4. Fully backward-compatible: If windowIdleTimeout is absent from the command payload, the extension uses the new 10-minute default. Old CLI versions work unchanged.

Usage

# Set idle timeout to 5 minutes (300 seconds)
export OPENCLI_WINDOW_IDLE_TIMEOUT=300
opencli browser open "https://example.com"
# Window stays alive for 5 min between commands

# Default (no env var): 10 minutes
opencli browser open "https://example.com"

Testing

Tested locally on macOS with Chrome + Browser Bridge Extension v1.0.0:

• ✅ Without env var: window survives 60s+ idle (was closing at 30s)
• ✅ With OPENCLI_WINDOW_IDLE_TIMEOUT=10: window closes after ~10s idle
• ✅ opencli browser close still works for explicit cleanup
• ✅ Adapter commands still auto-close immediately (unchanged behavior)