fix(desktop): stop installing a hybrid plugin's desktop half twice

[ocuclaw]

What does this PR do?

On a local backend a unified package's desktop half is served from the package copy on every install path, including the already-installed retry. The install flow no longer creates the second on-disk copy from #100412.

What main still did. plugin-install-modal.tsx::handleInstall gates the package path on agentInstalled && desktopHalfFromPackage (main :250). On a no-Force retry of a package already on disk the agent install returns Plugin '<name>' already exists. Use force reinstall (hermes_cli/plugins_cmd.py:789), agentInstalled stays false, and the modal falls through to installDesktopPlugin (main :263), which clones desktop-plugins/<git-name>/ next to the desktop-plugins/<manifest-name>/ copy that reconcileDesktopPlugins() already materialised. Two folders, one plugin id. Since #118902 (e1a6679399) the loader shows the second as an error row instead of running both, but the install flow still creates it whenever the repo's git name differs from its manifest name: (same-name retries are refused by desktop-plugin-install.ts:410-414 and create nothing). The comment at main :176-179 already states the invariant this violates: only a remote backend or a desktop-only repo needs a separate desktop clone.

Case (local backend, hybrid repo, both boxes ticked)	Before	After
No-Force retry, repo name != manifest name	agent error + desktop-plugins/<git-name>/ cloned beside <manifest-name>/	agent error only, one folder
Fresh install, agent clone fails	agent error + standalone desktop clone (duplicated by the next successful install)	agent error only, nothing left behind
Fresh install, agent ok	package half materialised	unchanged
Remote backend	separate clone	unchanged

Related Issue

Fixes #100412 (install-time half; the runtime half landed in #118902). Supersedes the install-side scope of #100485.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• apps/desktop/src/app/settings/plugin-install-modal.tsx::handleInstall: the package path is taken whenever desktopHalfFromPackage holds, whatever the agent install returned; reconcileDesktopPlugins() is idempotent so a retry touches nothing. The desktop success toast is raised only when the agent half landed or a copy was actually materialised, so a refused install shows the agent error alone.
• apps/desktop/src/app/settings/plugin-install-modal.test.tsx: two invariant tests, see below.

Validation

A/B against origin/main by swapping plugin-install-modal.tsx (cp swap, same test file):

Test	main	fix
never clones the desktop half standalone when the agent install is refused	✗ (installDesktopPlugin called)	✓
still clones the desktop half for a remote backend	✓	✓

• npx vitest run --project ui src/app/settings/plugin-install-modal.test.tsx: 8 passed.
• npm run check:lint (tsc x3 + eslint): 0 errors (208 pre-existing warnings, none in the touched files).
• npm --prefix apps/desktop run build: renderer builds, assert-dist-built passes.

Live repro

Hermes Desktop built from 836b5f825 with a local backend on the same HERMES_HOME, fixture https://github.com/ocuclaw/hermes-hybrid-dup-repro (git name hermes-hybrid-dup-repro, manifest name hybrid-dup-repro), both boxes ticked, Install, then Install again without Force reinstall.

Step	main 836b5f8	fix
Install #1	toast Desktop plugin hybrid-dup-repro installed; ~/.hermes/desktop-plugins/ = hybrid-dup-repro/ with .hermes-package.json → ~/.hermes/plugins/hybrid-dup-repro/desktop	same
Install #2, Force off	dialog: Plugin 'hybrid-dup-repro' already exists. Use force reinstall or run 'hermes plugins update hybrid-dup-repro'.; ~/.hermes/desktop-plugins/ = hermes-hybrid-dup-repro/ (bare clone, no marker) and hybrid-dup-repro/	same dialog error; ~/.hermes/desktop-plugins/ = hybrid-dup-repro/ only
Capabilities → Plugins	second row hermes-hybrid-dup-repro [Desktop] [on disk] [failed]: duplicate id "hybrid-dup-repro", already loaded from …/desktop-plugins/hybrid-dup-repro/plugin.js	one row hybrid-dup-repro v0.1.0 Agent + Desktop git

~/.hermes/plugins/ holds one hybrid-dup-repro/ throughout in both runs.

How to Test

1. Local backend, a hybrid repo whose plugin.yaml name: differs from the repo name (e.g. https://github.com/ocuclaw/hermes-hybrid-dup-repro: repo hermes-hybrid-dup-repro, name hybrid-dup-repro). Settings → Plugins → Install from Git, both boxes ticked, Install.
2. ls ~/.hermes/desktop-plugins/: one folder, hybrid-dup-repro/, with .hermes-package.json.
3. Install the same URL again without Force reinstall. Before: a second folder hermes-hybrid-dup-repro/ appears and Capabilities → Plugins shows a duplicate id error row. After: still one folder, the dialog shows only the agent's "already exists" error.

Not changed (out of scope, deliberately)

• Desktop UI ticked with Agent unticked on a hybrid repo still clones a standalone copy; that is the user opting out of the package, and whether its agent half is already installed is profile-scoped state the dialog does not hold.
• A hybrid repo whose desktop entry is a root-level plugin.js (not desktop/plugin.js) is not served by the package door (desktop-plugins-root.ts::materializeDesktopHalf); the dialog's package path was already taken for that shape on main. Separate report if wanted.
• hermes plugins install from the CLI after a differently-named standalone clone still yields a pair at reconcile time; the loader's error row covers it (Desktop plugin loader: hung imports time out, timers die on disable, duplicate ids error, broken reloads retire stale code #118902).
• No i18n, docs or Electron changes. The 09-02 version of this PR (6120f4910, still reachable) probed an agentPluginsRoot IPC and exported resolveDiskPluginEntry; both went away in feat(desktop): Plugins is one row per plugin; desktop halves are app-level, never profile-scoped #107314 (248ff2d3e8), which landed the happy path this PR was opened for, so that design is dropped rather than rebased.

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass: N/A, renderer-only change (vitest above)
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: Ubuntu 24.04, Node 22

Documentation & Housekeeping

• I've updated relevant documentation: N/A, no contract change
• I've updated cli-config.yaml.example if I added/changed config keys: N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows: N/A
• I've considered cross-platform impact (Windows, macOS): no path handling added, the renderer calls the existing IPC

[ocuclaw]

Re-cut on main @ 836b5f8, one commit, force-pushed to the same branch; the 09-02 diff (6120f4910) is gone from the PR but still reachable. #107314 landed the happy path and removed the door that version probed, so this is now the remaining install-time case only: the no-Force retry that clones desktop-plugins/<git-name>/ beside the package copy. Body has the live before/after on a Desktop built from that sha, the A/B table and the repro steps. CI will need a maintainer approval to run on this fork.

[ocuclaw]

Landed via #121475 (035171c7c), cherry-picked with authorship kept. Thanks @OutThisLife.