fix(coding-agents): don't let one stray file abort the Claude import, and give Prime Agent the companion skill (#3771, #3772)

[nicoloboschi]

Summary

Two independent coding-agents fixes, both small enough to share a PR.

#3771 — a stray file aborted the whole Claude history import. claudeHistory prefilters ~/.claude/projects candidates by encoded NAME and hands each match to jsonlFiles, which gated on existsSync — TRUE for a regular file — and then readdirSync, which throws ENOTDIR. That escaped importLocalHistory, which documents that it never throws, and whose caller (importConversations in installer.ts) has no catch of its own: one junk entry killed the entire --import-conversations run instead of costing that entry.

The guard belongs in the listing rather than at the call site the issue suggested — jsonlFiles already owned "there is nothing here to list" via existsSync, and a stray file is that same case reached through a different errno. A listDir helper now holds it, which also closes the identical hole one level up (a regular file at ~/.claude/projects was equally fatal) and sheds a stat per candidate directory plus its TOCTOU window. The dsh reader already handles its own case with a try/catch and is left alone.

#3772 — Prime Agent never received the companion skill. It documents the same discovery roots the other skills-capable hosts use, so it can load the skill and today only does so by accident, when the user also runs Codex or dsh and it picks ours up from the shared ~/.agents root. installSkill/uninstallSkill are now wired into its adapter, into Prime Agent's own ~/.prime/agent/skills: uninstallSkill removes a fixed directory name, so installing to the shared root would make uninstall prime-agent delete Codex's and dsh's copy. Uninstall's skill removal sits outside the settings.json guard so a hand-deleted settings file can't strand the skill.

Closes #3771.
Closes #3772.

Type of change

• Feature
• Bug fix
• Hotfix
• Spike / exploration
• Documentation
• Refactor

Test plan

• src/core/history.test.ts — two new Claude regression tests: a stray file named like the project dir of a subdirectory (so the prefix filter hands it to the listing), and a regular file where ~/.claude/projects itself belongs. Both were verified to fail on the pre-fix listing with the exact reported error (ENOTDIR: not a directory, scandir '…/.claude/projects/-Users-x-dev-myrepo-sub'), and the first still imports the real session alongside the junk entry.
• src/installer.test.ts — prime-agent joins the cross-host skill install/uninstall matrix, plus a test that installing Codex and Prime Agent and then uninstalling Prime Agent leaves the shared ~/.agents copy intact.
• npx vitest run --exclude 'src/e2e/**' → 658 passed, 23 skipped. ./scripts/hooks/lint.sh clean, ./scripts/hooks/check-unused.sh shows nothing new.
• README regenerated through npm run skill:build + sync-coding-agents-doc.mjs after linting; only the docs page moved, the skill regions are untouched.

Notes for the reviewer

• There are two open community PRs against these issues, opened before this one: fix(coding-agents): don't let a stray file at the dsh sessions root abort the history import #3778 (coding-agents: --import-conversations dies on a stray file in ~/.claude/projects instead of skipping it #3771) and feat(coding-agents): first-class pi support, sharing one extension adapter and installer with Prime Agent #3775 (coding-agents: Prime Agent never gets the companion skill, though it discovers the same skill roots pi does #3772, bundled with adding pi as a new harness). This PR takes the same listDir shape as fix(coding-agents): don't let a stray file at the dsh sessions root abort the history import #3778 for the first half, and does the Prime Agent half without the new harness. Close whichever set you don't want.
• Prime Agent is not added to SKILL_DIRS in core/skill-sync.ts: that self-update path runs from the stdin hook session-start, which persistent-plugin harnesses (prime-agent, dsh, opencode, Kilo, Cline) never reach — the known dsh adapter: daemon mode never starts the daemon (ensureDaemon parity missing) #3524-shaped gap, unchanged here. Prime Agent's copy refreshes on re-install like dsh's does.
• Left alone as behaviour changes rather than this fix: codexHistory's walk is guarded at the opposite altitude (one unstattable entry discards every file found so far), and importLocalHistory still has no top-level backstop for its never-throws contract.

🤖 Generated with Claude Code

https://claude.ai/code/session_01AHvpDBNP3CXfVL88WnazmC

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