[Bug] org-plugins skills unavailable until 10-minute periodic sync fires — race condition between SkillsPlugin sync and custom-3p:org-plugins install on every startup

Environment

• Claude Desktop (Cowork 3P mode)
• macOS
• App version: 1.9659.2 (390d6c) 2026-05-28

Description

When an org plugin is installed via /Library/Application Support/Claude/org-plugins/ with installationPreference: "auto_install", the plugin's skills are not available in Cowork on startup. They become available approximately 10 minutes after launch — exactly matching the SkillsPlugin periodic sync interval of 600,000ms.

This happens on every restart, not just the first.

Root Cause (from main.log)

SkillsPlugin sync and custom-3p:org-plugins install run concurrently on startup. SkillsPlugin consistently completes and writes the skills manifest before custom-3p:org-plugins finishes installing the org plugin. The next sync doesn't fire until 600,000ms later.

The pattern is identical across all observed restarts (8 consecutive restarts logged):

2026-06-01 13:41:00 [info] [SkillsPlugin] Starting skills sync
2026-06-01 13:41:00 [info] [SkillsPlugin] Found 0 enabled skills
2026-06-01 13:41:00 [info] [SkillsPlugin] Sync complete: no remote skills, built-in skills written   ← writes manifest WITHOUT org plugin
2026-06-01 13:41:00 [info] [custom-3p:org-plugins] Installed my-plugin@org-provisioned (1.0.0)      ← arrives too late
2026-06-01 13:41:00 [info] [LocalPluginsWriter] Set plugin enabled=true in settings: my-plugin@org-provisioned
2026-06-01 13:41:00 [info] [custom-3p:org-plugins] Auto-installed 1 org plugin(s)

Same sequence across all 8 restarts — timestamps are identical to the second, but log ordering shows SkillsPlugin consistently completes before org-plugins install. The next SkillsPlugin sync fires 10 minutes later:

2026-06-01 13:41:00 [info] [SkillsPlugin] Starting periodic sync (interval: 600000ms)
...
2026-06-01 13:51:00 [info] [SkillsPlugin] Starting skills sync   ← first opportunity to pick up installed plugin

Reproduction Steps

1. Place a valid plugin in /Library/Application Support/Claude/org-plugins/my-plugin/ with "installationPreference": "auto_install" in .claude-plugin/plugin.json
2. Launch Claude Desktop (Cowork 3P mode)
3. Open Cowork immediately — plugin skills are not available
4. Wait ~10 minutes — skills appear without any user action

Expected Behavior

Org plugin skills should be available immediately on startup, or at minimum SkillsPlugin sync should wait for custom-3p:org-plugins install to complete before writing the skills manifest.

Workaround

None. The 10-minute delay occurs on every restart.