Add claude-memory-tidy to Memory & Context Management

[tonydzi]

Adds one resource to Memory & Context Management.

What it is

claude-memory-tidy — a small deterministic toolkit that keeps Claude Code's always-loaded MEMORY.md index healthy on macOS/Linux.

The problem it addresses

MEMORY.md is loaded into every session, and past a fixed size the harness truncates it with no error. The tail silently disappears and the agent stops knowing things it "remembers". Separately, notes accumulate on disk that nothing points at — present but unreachable, which at recall time is the same as deleted.

What it does

• Guard (no LLM): budget, over-length entries, orphaned notes, dead pointers, duplicate slugs, sync-conflict files.
• Orphan coverage (no LLM): gives every unreachable note a pointer in the not-auto-loaded archive, using the note's own description: — transcription, not invention, and it costs zero live-index budget.
• Folding (no LLM): moves a domain into a warm hub-*.md sub-index verbatim, and refuses to write at all if any folded note would lose reachability. This guards against summary-grounding, where a model rewrites a hook "while it's in there" and the disambiguating detail evaporates.
• Tidy runner: cheap detectors gate the model, so a quiet day costs ~0 tokens; afterwards the guard re-verifies, because the model's own summary of its work is not evidence.
• Declared ownership: prevents a second writer on an index synced byte-identically from another machine.

Measured on one real run: 26 275 B / 164 lines / 112 orphans → 8 606 B / 52 lines / 0 orphans. Nothing deleted.

Checklist

• Actively maintained — yes, in daily use on the machine it was built for
• Clear documentation — README plus an installable SKILL.md
• Real value to Claude users — addresses a silent failure mode of always-loaded memory
• One resource, one PR

MIT, Python stdlib only, no network calls, no telemetry. 17 tests run against a temporary fixture (python3 tests/test_memory_tidy.py), so they pass on any machine and never touch real memory.