fix(skills): name the remove command when install refuses a duplicate

[redswimmer]

Outcome

skill install refuses to replace a skill that is already in the canonical writable root. Before, the refusal didn't say how to recover. Now it ends with the exact command to run, for example Remove it first with: nemoclaw alpha skill remove code-review.

Reason

Agents without a native add command, such as Hermes, use the canonical-root fallback. When a skill was already installed, users had to look up or guess the supported removal command.

Related issues

Fixes #12668

Changes

• buildCanonicalSkillAddCommand takes an optional remove command and prints it in the refusal. It is passed to printf as a quoted argument, not interpolated into the format string.
• installSandboxSkill passes <cli> <sandbox> skill remove <name>.
• Tests: a Linux-only test runs the generated script against an existing skill and checks the exit code, the hint, and that the existing skill is unchanged. It reuses the existing staging helper. An action-level test checks that the sandbox-scoped command is passed through.

Verification

• Live Hermes sandbox, NemoClaw built from source, OpenShell 0.0.116, OpenRouter. A second skill install on main exited 1 with the issue's message. On this branch it exited 1 and printed Remove it first with: nemoclaw skilltest skill remove code-review. Running that command and then installing again exited 0.
• npx vitest run src/lib/skill-install.test.ts src/lib/actions/sandbox/skill-install.test.ts passed (48 tests). Both new (#12668) tests fail without the fix.
• npm run test:titles:check, npm run source-shape:check, tsc -p tsconfig.cli.json, oxfmt and oxlint all passed.
• The diff contains no secrets, API keys, or credentials.

Review notes

The local pi-qualification-receipt-refresh and hadolint hooks also fail on unmodified main, so they were skipped for this push. This change touches neither area.

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Signed-off-by: Andrew Savala andrew@redswimmer.com

Summary by CodeRabbit

• Bug Fixes
  • When adding a skill would overwrite an existing skill, installation now stops and leaves the existing files unchanged.
  • The error message provides a command to remove the conflicting skill when available, or guidance for managing native skills otherwise.
  • Hermes fallback instructions now include the relevant skill removal command, scoped to the sandbox and skill being installed. This helps identify the conflicting skill and the appropriate removal action.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 972dcf4 and f573e14.

📒 Files selected for processing (2)

• src/lib/actions/sandbox/skill-install.test.ts
• src/lib/skill-install.test.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• src/lib/actions/sandbox/skill-install.test.ts

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📝 Walkthrough

Walkthrough

The canonical skill-add command accepts an optional removal command and includes it in the refusal when a skill destination already exists. The sandbox action supplies a sandbox-scoped removal command.

Changes

Canonical skill installation

Layer / File(s)	Summary
Existing-skill refusal and test coverage src/lib/skill-install.ts, src/lib/skill-install.test.ts	The canonical skill-add command accepts an optional removal hint and includes it when refusing an existing destination. The Linux-only test checks the hint, exit status, and preservation of the existing file. Test setup now uses a shared staging helper.
Sandbox removal-command wiring src/lib/actions/sandbox/skill-install.ts, src/lib/actions/sandbox/skill-install.test.ts	The sandbox action passes a sandbox-scoped removal command to the canonical skill-add command. The fallback test checks the generated command.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: cv

Merge Risk: ⚪ Minimal · up to f573e

The change provides sandbox-scoped removal guidance while refusing to replace an existing canonical skill. The inspected quoting and refusal path reveal no actionable merge-blocking risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: duplicate-skill install refusals now name the removal command.
Linked Issues check	✅ Passed	Issue #12668 requires the canonical-root fallback to refuse replacement, preserve the existing skill, and show the supported removal command. The prior reviewed evidence establishes that `buildCanonic…
Out of Scope Changes check	✅ Passed	The current incremental changes add comments that describe temporary test fixtures and a test shim. These comments relate to the issue’s regression tests. The previous assessment found the whole-PR ch…
Docstring Coverage	✅ Passed	Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 4 files.

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