[BUG] Cowork/claude.ai: uninstalling "Installed by default" marketplace plugins silently reverts within ~60s — no opt-out, "Enable plugin" toggle also reverts

Summary

Plugins flagged "Installed by default" in the official knowledge-work-plugins marketplace are re-installed server-side within ~60 seconds of a user uninstalling them on claude.ai → Customize. The uninstall UI reports success (confirmation dialog, plugin disappears, redirect), then the plugin silently returns on the next server fetch. The per-plugin "Enable plugin" toggle also reverts to on after a page reload. There is no visible indication that these plugins will be auto-restored, and no user-facing opt-out.

Environment

• Claude Desktop (Cowork) on macOS + claude.ai web (Chrome), personal account (user is their own org admin — no company policy involved)
• Marketplace: knowledge-work-plugins (Anthropic & Partners)
• Date: 2026-07-06

Instrumented reproduction (all clients verifiably closed)

Scripted run, timestamps from tonight:

01:53:19  Claude Desktop confirmed quit (pkill/pgrep verified)
01:53:40  operations uninstalled via claude.ai UI (kebab -> Uninstall -> confirm) — verified GONE
01:54:43  brand-voice, engineering, apollo, productivity likewise uninstalled — all verified GONE
01:55:41  poll 1 (~60s later): operations INSTALLED again  <- resurrection, no client running
01:56-02:06  polls 2-12 every ~60s: stays INSTALLED; local app closed throughout
02:06:31  final verify: all 5 plugins re-installed

Reproduced 4x across the night (2-min, 10-min, and instrumented 12-min watches).

The differential that identifies the mechanism

• Always resurrect: operations, brand-voice, engineering, apollo, productivity
• Stay uninstalled permanently: marketing, design, sales, product-management, enterprise-search (same marketplace, uninstalled the same way)

This matches the "Installed by default" installation preference described in the support article "Manage Claude Cowork plugins for your organization" — but for a consumer/personal account with no way to see or change that flag.

What was tried

1. Uninstall via claude.ai UI → reverts ≤60s (see timeline)
2. Uninstall with the desktop app fully quit → same
3. Per-plugin "Enable plugin" toggle off → reverts to on after reload
4. Purging the local Cowork plugin manifest (…/rpm/manifest.json) → local sessions stop loading the plugins (effective client-side), but the server-side "installed" state remains wrong

Expected behavior

Either (a) a user's uninstall of a default-flagged plugin persists on consumer accounts, or (b) the UI clearly states "this plugin is installed by default and will be re-added automatically" with an opt-out. Currently the uninstall silently succeeds-then-reverts, which reads as data loss / ghost behavior and cost several hours to root-cause.

Impact

Users who curate their plugin set (context/token budget, latency) cannot remove these plugins; each one ships multiple skills that load into session context. The silent revert also masquerades as a sync bug, inviting fruitless local debugging.