TASK-IMP-126: Uninstall completeness - MCP, dangling skill links, hook newline

Summary

uninstall.sh is not the inverse of install.sh in three places. It never removes the MCP registration files install writes, it cleans only two of the agent families' skill entries and leaves the rest pointing at the deleted machine, and its hook-strip leaves a blank line behind that accumulates on every install/uninstall cycle. Make uninstall the exact inverse of install for these three artifacts, proven by a fixture that installs, uninstalls, and asserts the tree is clean.

Problem

Three verified gaps, each a place where install writes and uninstall does not remove.

Dead MCP registrations. install.sh:694-697 writes .mcp.json (and .cursor/mcp.json when the cursor agent is selected), each pointing at .cyberos/mcp/cyberos-mcp.mjs. uninstall.sh contains zero MCP handling (grep -ci mcp = 0). After uninstall removes .cyberos/, those files survive and register an MCP server whose entry point no longer exists - a broken registration every MCP-capable agent reads.

Dangling skill links. install.sh:632-637 installs the workflow skills for the claude-code, grok, command-code, codex, and opencode families, each a symlink (or copy-fallback) into .cyberos/plugin/skills/. uninstall.sh:98-127 removes only the .agents/skills trio and the .claude/skills create-tasks pair, and :125 explicitly leaves .claude/skills/ship-tasks. The grok, command-code, codex, and opencode entries are never touched. After .cyberos/ is removed, every untouched managed link dangles.

Hook-strip newline leak. install.sh:860-861 appends the managed block to a foreign pre-commit hook via a heredoc whose first line is a blank separator, writing \n# >>> cyberos-status-hook v2 ...>>>\n...\n# <<< cyberos-status-hook <<<\n. uninstall.sh:78 strips the marked range with sed '/# >>> .../,/# <<< ...<<</d' - inclusive of both markers but not the leading blank. The separator survives, so each install/uninstall cycle on a foreign hook accumulates one blank line at the append point. The v1->v2 upgrade path (install.sh:856) shares the pattern.

Proposed Solution

Make uninstall the inverse of install for all three, keeping the whole change in uninstall.sh plus arms in the existing test_install_hygiene.sh:

• Remove .mcp.json and .cursor/mcp.json when they are the cyberos-written form, never when they are an operator's own file (same ownership discipline the skill and hook sections already use - match the exact content install writes, or a marker).
• Extend the skill-cleanup loop to cover every family install writes (grok, command-code, codex, opencode) plus .claude/skills/ship-tasks, removing an entry only when it is ours by construction: a symlink whose readlink target resolves into .cyberos/plugin/skills, or a copy carrying the .cyberos-owned marker.
• Widen the hook-strip so it consumes the leading blank separator, leaving a foreign hook byte-identical to its pre-install content across any number of cycles.

Alternatives Considered

• Fix the newline on the install side (drop the leading blank from the heredoc). Rejected: the blank is a deliberate readability separator in a hook an operator reads, and the defect is that uninstall does not undo what install does - the inverse belongs in uninstall, next to the strip that already exists.
• Three separate tasks, one per finding. Rejected at the PLAN gate: all three live in uninstall.sh and would serialise on one file with no benefit (recorded 2026-07-19).
• Have uninstall shell out to a manifest of what install wrote. Rejected: no such manifest exists, and ownership-by-construction (readlink target / marker / exact content) is the discipline the file already uses and is enough.

Success Metrics

• Primary: a fixture install then uninstall leaves zero cyberos-owned artifacts - no .mcp.json/.cursor/mcp.json we wrote, no skill link resolving into the removed machine, and a foreign hook byte-identical to before install - suite-asserted. Baseline: all three survive today.
• Guardrail: no operator file is removed - an operator's own .mcp.json, an unmarked .agents/skills/<cmd> dir, and the foreign hook's own lines all stay (the existing spec 1.3 "never touch operator files" promise is not weakened).

Scope

In scope: uninstall.sh's MCP-file removal, the skill-cleanup coverage, the hook-strip separator, and arms in test_install_hygiene.sh.

Out of scope / Non-Goals

• Any change to install.sh (what install writes is correct; uninstall is what is missing).
• The $HOME global installs behind CYBEROS_GLOBAL_SKILLS=1 (opt-in, default off) - a follow-up may cover them, but the default-path fleet does not create them and this task stays on the always-created artifacts.
• The rules_sha fingerprint (TASK covered separately; judged by-design at the PLAN gate).
• Re-installing the fleet (that is Goal 4, an operator-gated action).

Dependencies

None blocking. Touches uninstall.sh (shared surface with TASK-IMP-083 hook logic and TASK-IMP-094 skill logic - both already landed; this extends their inverse coverage).

AI Authorship Disclosure

• Tools used: Claude (Fable 5) running the CyberOS task-author skill inside Cowork.
• Scope: spec drafted from the 2026-07-19 fleet-health pass; each of the three gaps was verified against the live install.sh and uninstall.sh at HEAD with the exact line numbers cited in source_pages. The handoff's "5 dangling symlinks" count was deliberately not adopted as a normative number - it cannot be verified without a live install, so 1.2 specifies the invariant (zero dangling links) and the test proves it against a fixture.
• Human review: scope and granularity approved at the 2026-07-19 PLAN gate; both HITL gates are recorded human verdicts.

1. Description (normative)

• 1.1 uninstall.sh MUST remove .mcp.json and, when present, .cursor/mcp.json when they are the cyberos-written form (their content matches what install.sh writes, or they carry a cyberos marker), and MUST NOT remove an operator's own file of either name.
• 1.2 uninstall.sh MUST remove every managed skill entry install created that resolves into the removed machine - across all agent families install writes (claude-code, grok, command-code, codex, opencode) plus .claude/skills/ship-tasks - leaving zero symlinks that point into .cyberos/plugin/skills after the machine is removed. Ownership MUST be proven by construction (readlink target resolving into .cyberos, or the .cyberos-owned marker); an unmarked operator dir MUST be left in place.
• 1.3 The hook-strip MUST be the exact inverse of install's append: it MUST also remove the leading blank separator install writes before the >>> marker, so a foreign pre-commit hook is byte-identical to its pre-install content after uninstall, and stays byte-identical across any number of install/uninstall cycles.
• 1.4 None of 1.1-1.3 may remove an operator file: an operator-authored .mcp.json, an .agents/skills/<cmd> dir without the .cyberos-owned marker, or any line of a foreign hook outside the managed block MUST survive uninstall.

2. Acceptance criteria

• [ ] AC 1 (traces_to: #1.1) - a fixture install writes .mcp.json; uninstall removes it; a pre-existing operator .mcp.json is left untouched - test: tools/install/tests/test_install_hygiene.sh::t_mcp_registration_removed
• [ ] AC 2 (traces_to: #1.2) - after a fixture install then uninstall, zero skill links resolve into the removed .cyberos/plugin/skills (checked across every family install writes) - test: tools/install/tests/test_install_hygiene.sh::t_no_dangling_skill_links
• [ ] AC 3 (traces_to: #1.3) - install then uninstall then install then uninstall on a foreign pre-commit hook leaves it byte-identical to the original (no accumulated blank line) - test: tools/install/tests/test_install_hygiene.sh::t_hook_strip_byte_identical_across_cycles
• [ ] AC 4 (traces_to: #1.4) - an operator .mcp.json, an unmarked .agents/skills/<cmd> dir, and a foreign hook's own lines all survive uninstall - test: tools/install/tests/test_install_hygiene.sh::t_operator_files_preserved

3. Edge cases

• The v1->v2 hook upgrade path (install.sh:856) shares the leading-blank append shape; the widened strip MUST heal a v1 leftover too, not only a v2 block.
• .cursor/mcp.json exists only when the cursor agent was selected at install; uninstall MUST remove it when present and MUST NOT fail when absent.
• Skill entries that landed as copy-fallbacks (no symlink support, or CYBEROS_COPY_SKILLS=1) are removed only when they carry the .cyberos-owned marker - a copy an operator made is byte-indistinguishable without it and MUST stay.
• A hooksPath repo (core.hooksPath set) writes the hook outside .git/hooks; the strip MUST operate on the effective hooks dir the same way install and the existing strip do.
• Security-class: uninstall reads paths and file content and executes nothing. Paths are confined under the repo root on the same relUnderRoot rule the other helpers use; a crafted target cannot walk out.