Fourth review on PR #947 reported two functional bugs, explicitly noting it had not run anything. Both reproduced, and the first is severe. 1. F1 -- the blocking gate -- could be bypassed by a typo. _check_forgetting_rule() failed only when `rule` was literally "none"/""/"never", and otherwise inferred PASS from what the rule was *not*. So anything unrecognized fell through to the PASS branch with an empty mechanism list. Reproduced: {"rule": "asdf"} -> F1=PASS "Forgetting is designed: ." {"rule": "ttl"} (no ttl_days)-> F1=PASS "Forgetting is designed: ." A misspelling silently passed the one check this entire skill is built around, and the nonsensical detail string was the only hint. The check is now allowlist-based: PASS is unreachable unless a concrete mechanism is actually found (ttl_days > 0, max_records/max_bytes > 0, or a decay setting). Failure messages now distinguish an unrecognized rule from a declared-but-unconfigured one, so a typo is never mistaken for a deliberate decision not to forget. Booleans are rejected where a number is expected, and ttl_days=0 counts as absent. Verified across 10 cases: all six bypass variants now FAIL at exit 4, all four legitimate mechanisms still PASS, and the empty-mechanism string can no longer be emitted. 2. --print-sample-spec was unreachable on all three scripts that offer it. The flag sat outside a mutually-exclusive group declared required=True, and argparse enforces that during parse_args() -- before any of our code runs. So the flag alone exited 2 with a usage error, which broke the first line of the workflow SKILL.md documents verbatim: python scripts/memory_cost_profiler.py --print-sample-spec > workload.json The group is now required=False with explicit post-parse validation, so no-args still errors helpfully and names all valid entry points. Verified the full round-trip on all three: --print-sample-spec > f.json, then feed f.json back in. This slipped through because the PR's own checklist covered --help, --sample and --output json, but never ran --print-sample-spec standalone. Also removed the identity dict in render() flagged as a nit. Verified: 4/4 scripts help/sample/json; error paths 3/4/4; all six blocking gates; checklist 6/6 PASS; security auditor PASS (0 critical, 0 high, 0 info). Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Jt1sqt5kQmopyfXu2Hhjnv
memory-engineering
Your agent's problem was never that it forgets. It's that it never forgets on purpose.
A storer optimizes what a system remembers. A memory engineer optimizes what it forgets. This plugin makes that shift executable: four deterministic stdlib scripts that price the write path, choose which cost to pay, audit what a store actually holds, and refuse a design with no forgetting policy.
Why this exists
Everyone building agent memory optimizes retrieval. Almost nobody engineers what it costs to build, what is worth keeping, who can delete it, and where it lands on the hardware. Stanford's systems characterization of ten memory systems found the gap concretely:
- Construction energy exceeds total query-phase energy across 300 queries — the bill is paid on the write path you never watch.
- Energy per correct answer spreads more than 47× across systems (BM25 at 4,145 J; MIRIX at ~197 kJ).
- At 1M tokens, footprint varies up to 9× — and "none of the evaluated systems prune or forget by default."
If you did not build forgetting, you do not have it.
Install
/plugin marketplace add alirezarezvani/claude-skills
/plugin install memory-engineering
Use
/cs:memory-engineering ~/.claude/memory # full four-lens pass
/cs:forgetting-audit design.json # just the blocking gate
Or run the scripts directly — each has --help, --sample, and --output json:
cd skills/memory-engineering
python scripts/memory_cost_profiler.py --sample
python scripts/memory_architecture_picker.py --sample
python scripts/memory_density_auditor.py --dir ~/.claude/memory
python scripts/forgetting_policy_linter.py --sample-failing
The four scripts
| Script | Lens | What it does | Exit codes |
|---|---|---|---|
memory_cost_profiler.py |
Stanford — what does it cost? | Splits construction vs query spend, computes cost per correct answer, flags under-amortized writes and construction co-located with live queries | 0 · 2 finding · 3 bad input |
memory_architecture_picker.py |
Stanford — which cost to pay? | Scores long-context / flat RAG / structure-augmented RAG / agentic against constraints, disqualifies on hard limits, names the cost you're choosing, refuses to pick on a tie | 0 · 2 ambiguous · 3 bad input · 4 none viable |
memory_density_auditor.py |
Microsoft — what's worth keeping? | Classifies records FACT / SKILL / LOG / PROSE, finds near-duplicates, flags stale and time-relative wording, scores knowledge density. Runs on a real directory or JSONL | 0 dense · 2 finding · 3 bad input |
forgetting_policy_linter.py |
Anthropic + the gate | 8 checks; F1 (explicit forgetting rule) and F4 (contradictions surfaced, never auto-merged) are blocking | 0 PASS · 2 CONDITIONAL · 4 FAIL |
Stdlib only. No network, no LLM calls, no dependencies.
The gate
$ python scripts/forgetting_policy_linter.py --sample-failing
VERDICT: FAIL (0/8 checks pass)
This design does not forget on purpose. F1 failed. F4 failed.
FAIL F1 explicit forgetting rule [BLOCKING]
No TTL, no capacity bound, no decay. The store only grows.
FAIL F4 contradictions surfaced, never auto-merged [BLOCKING]
Contradiction policy is 'newest_wins', which resolves conflicts silently.
F4 is blocking on purpose. Two memories that disagree may both have been true in different contexts — "deploys go through Jenkins" and "deploys go through GitHub Actions" is not a contradiction to resolve, it is a migration to record. Auto-merging destroys the only evidence the conflict existed.
Evidence discipline
The four-lens framing synthesizes "How to be a Memory Engineer, from the perspective of Stanford, Microsoft, Anthropic and Nvidia" by @N01ennn.
Every quantitative claim is cited to the primary source, not to that article, and each carries an explicit confidence level. Two of the article's paraphrases are corrected in the references:
- The 47× energy figure is the spread across ten evaluated systems, not
"two systems with identical accuracy" (
memory_cost_canon.md§2). - The 97% first-pass-error reduction is Rakuten's named, vendor-published
customer testimonial — not a controlled study or a general property of
building memory this way (
memory_control_and_governance.md§4).
Not this plugin
| You want | Use |
|---|---|
| Build and maintain one markdown knowledge vault | llm-wiki |
| A nightly self-improvement loop over transcripts | skillopt-sleep |
| Bound an agent's task loop | agent-harness |
| Price inference generally | llm-cost-optimizer |
This bounds a store, not a loop and not a vault.
Primary sources
- Omri, Y. et al. — Agent Memory: Characterization and System Implications of Stateful Long-Horizon Workloads, arXiv:2606.06448
- Microsoft Research — PlugMem: A Task-Agnostic Plugin Memory Module for LLM Agents
- Kontonis, V. et al. — MEMENTO: Teaching LLMs to Manage Their Own Context, arXiv:2604.09852
- Anthropic — Built-in memory for Claude Managed Agents
Full citation lists (7 sources each) are in
skills/memory-engineering/references/.
License
MIT.