Battam1111/Myco

v0.5.20 — 2026-04-23 — Cowork plugin install: retraction + drag-drop fix

v0.5.19 shipped a broken installer. This release retracts the
"permanent fix" framing and delivers the actual permanent fix.

What v0.5.19 claimed vs what actually happened

v0.5.19's myco-install cowork-plugin wrote a plugin tree into
<APPDATA>/Claude/local-agent-mode-sessions/<owner>/<ws>/rpm/plugin_myco/
and upserted an entry in each rpm/manifest.json. The release
changelog described this as "the permanent fix for agent onboarding
in Cowork." It is not. Cowork's [RemotePluginManager] regenerates
rpm/manifest.json from an Anthropic cloud marketplace on every
session start, and sync runs drop any plugins[] row that does not
correspond to a cloud entry — the v0.5.19 writes are wiped silently
between sessions.

Symptom (as reported on 2026-04-23): after restart and a fresh Cowork
session, the myco-substrate skill was missing from the agent's
available-skills list even though the installer exited zero a moment
earlier. Direct inspection confirmed rpm/manifest.json no longer
contained the plugin_myco row we wrote.

Root cause

The source of truth for Cowork plugins is an Anthropic cloud
marketplace (marketplace_01UDYDZqTLSQBkNqpTGCfzNM for account
uploads), not the local rpm/ directory. Claude Desktop's drag-drop
UI POSTs the bundle to
https://api.anthropic.com/api/organizations/{orgId}/marketplaces/{marketplaceId}/plugins/account-upload,
and the server-side record is what every Cowork session syncs from.
rpm/ is a cache, never a source. Reading the decompiled
app.asar:433299-433340 confirmed this end-to-end.

v0.5.20 fix

• New src/myco/install/plugin_bundle.py: builds a
  myco-<version>.plugin ZIP (single top-level dir myco/ holding
  .claude-plugin/plugin.json + .mcp.json + skills/myco-substrate/
  — the layout Claude Desktop's upload handler validates against).
• New scripts/build_plugin.py: thin CLI wrapping the library;
  the GitHub Release workflow now runs it and attaches the .plugin
  as a release asset, so users can either curl -L the latest or
  python scripts/build_plugin.py from a repo checkout.
• myco-install cowork-plugin rewritten: drops the rpm/ writer
  entirely. Default action now builds the bundle, prints exact
  drag-drop instructions, and exits. --cleanup-legacy removes
  v0.5.19-era cruft (rpm/plugin_myco/ dirs + manifest rows).
• myco-install host cowork + --all-hosts: the flow that
  auto-ran the (broken) plugin install now builds the bundle and
  prints upload instructions instead. Uninstall paths are silent —
  removing the plugin is a user action in Claude Desktop's UI.
• Legacy-function regression guard: the old
  install_cowork_plugin() function now raises RuntimeError with a
  migration message, so any script that still imports it gets a loud
  failure rather than a silent wrong install.
• Release workflow: .github/workflows/release.yml adds a
  .cowork-plugin/plugin.json version check alongside the existing
  four-file parity gate, builds the .plugin, and uploads it via
  gh release upload with --clobber for idempotency.

What did NOT change

• R1–R7 rule text. Unchanged.
• Category enum / exit-policy / exit codes. Unchanged.
• 18-verb manifest. Unchanged.
• 25 lint dimensions. Unchanged.
• Claude Code plugin bundle (.claude-plugin/ at repo root).
  Unchanged — that install path works correctly and was never
  affected by the rpm/ misunderstanding.

Break from v0.5.19

Cosmetic. The CLI still has myco-install cowork-plugin, but its
flags and behavior differ: --uninstall is gone (no CLI uninstall —
remove through Claude Desktop UI), replaced with --cleanup-legacy;
new --output controls where the .plugin file is written.
Anyone whose v0.5.19 install "succeeded" should run:

myco-install cowork-plugin --cleanup-legacy

to scrub the residue, then follow the drag-drop upload flow below.

Operator action

# 1. MCP config (write once)
myco-install host cowork

# 2. Build the .plugin bundle
myco-install cowork-plugin
# or:
curl -L -o myco.plugin https://github.com/Battam1111/Myco/releases/latest/download/myco.plugin

# 3. Drag dist/myco-<version>.plugin into Claude Desktop:
#    Settings → Plugins (or Extensions) → Upload → select the file
# 4. Restart any open Cowork session

Full rationale + screenshots: docs/INSTALL.md § 1.1.

Lesson

v0.5.19 shipped a fix whose correctness I verified only by checking
the post-install filesystem state, not by checking the post-restart
filesystem state. The regression shipped because "installer wrote to
disk successfully" and "plugin persists across restarts" are
different claims and I tested only the first. Future host-axis
installers must be tested end-to-end across a session restart before
shipping a "permanent fix" label.