fix(admission): a busy process outside any repository is host load, not uncovered work of unknown ownership #294

Problem

dot admit deferred agent-hub's local checks five times on 2026-10-20 (exit 75). Each time the blocker was a background process that runs no build or test, in no repository:

• Maru's dotfiles commands (parent Maru.app), reported as dotfiles(pid=...,parent=8703,repo=);
• claude-mem's observer, a one-turn headless claude --max-turns=1 summarizer whose cwd is ~/.claude-mem/observer-sessions.

Cause, in internal/admission/uncovered.go:

• unownedHeavyJobs counts any row at 100% CPU or more as heavy, whatever its name (heavyweight(...) || r.cpu >= 100).
• resolveJobDirectories resolves the cwd, and repositoryIdentity fails when the walk reaches / without a .git. That leaves Repository empty.
• filterUncovered treats an empty Repository as unknown ownership and blocks every caller.

So a busy process whose cwd is known and lies outside every repository (an app launched with cwd /, or a tool's state directory) blocks all admission in every repository. Its CPU use is host load, which the pressure thresholds already cover.

Decisions

• D1: repositoryIdentity returns a sentinel (errNotRepository) when the walk ends without finding .git. Every other failure (permission, invalid Git pointer, symlink error) stays a plain error, meaning unknown.
• D2: HeavyJob records two facts:
  • CPUOnly: the row matched only the CPU rule, not heavyweight(name, args);
  • OutsideRepository: its cwd was observed and repositoryIdentity returned errNotRepository.
• D3: filterUncovered no longer counts a job that is both CPUOnly and OutsideRepository as unknown ownership. The maintenance rule is unchanged: a maintenance-shaped job still blocks the maintenance class.
• D4: unchanged:
  • build- or test-shaped work outside a repository still blocks;
  • a job whose cwd could not be observed (lsof failure, partial batch) still blocks;
  • the 20-job inventory cap and the pressure thresholds are unchanged.

Acceptance criteria

• AC1: filterUncovered drops a CPUOnly && OutsideRepository job, and still blocks:
  • a CPU-only job of unknown ownership (cwd unobserved, or a non-sentinel resolution error);
  • a heavyweight-shaped job outside a repository;
  • a maintenance-shaped CPU-only job outside a repository for the maintenance class (table test).
• AC2: repositoryIdentity returns errNotRepository for a temporary directory with no .git above it, and a plain error for an invalid Git pointer (test).
• AC3: unownedHeavyJobs sets CPUOnly only when the CPU rule alone matched (test with claude at 150% CPU and cargo build at 150% CPU).
• AC4: make test (GOMAXPROCS=2 -p 2 -parallel 2) and make lint pass; CI green.