field-borrow — borrow from the field, but witness the gap against yourself first

High-priority inspired-by default

This is the repository's high-priority default "inspired by" workflow. Invoke it proactively whenever a named product, repository, paper, standard, benchmark, release, issue, PR, roadmap, design discussion, or field practice could improve fak. Do not wait for an explicit research or borrowing request: run it before bespoke design when credible prior art may change the choice. External evidence does not override user scope, security, legal obligations, or coherent shipping.

Six laws govern every pass:

1. Priority: consider external prior art early, not as optional cleanup after designing.
2. Licensed reuse: copy or adapt directly when exact-source licensing and technical fit permit; fresh reimplementation is not inherently better.
3. Exhaustiveness: all relevant source classes were checked or explicitly marked unavailable.
4. Dating: every observation carries event time, observation time, source state, and refresh cue.
5. Breadth: mine implementation, docs, tests, history, releases, issues, PRs, discussions, roadmaps, and provenance—not only README claims.
6. Spirit: explore transferable principles and responsible extensions even when upstream has only a partial prototype; label inference separately from shipped fact.

Exhaustive, dated source ledger

For a repository-shaped source inspect canonical docs/design/API examples; code, tests, fixtures, and configuration at a pinned revision; releases/tags/changelog and relevant history/blame; open and closed issues; merged, closed, and open PRs plus review discussion; discussions, RFCs, ADRs, roadmaps, and TODOs; exact-revision LICENSE, per-file headers, NOTICE, vendored/generated provenance, submodules, and contribution terms. For papers/products/standards use equivalent primary sources (artifact/appendix, official release history, normative revision/errata). Follow citations to the mechanism's origin. Inaccessible surfaces are omissions, not empty results.

Record every material observation with:

• observed_at: full ISO date/time for the research observation;
• source_event_at: commit, merge, release, publication, or update date;
• source state: released/shipped, merged-unreleased, proposed/open, rejected/closed, experimental, or unclear;
• immutable anchor: path:line@full-sha, release/tag+digest, paper version/DOI, or standards rev;
• platform context: relevant version, API generation, provider, hardware, plan/tier, or environment;
• refresh trigger: release, PR merge, API rollover, benchmark rerun, or none known.

Never write timeless “X does Y” for a changing platform. Open issues, PRs, and roadmaps prove interest/direction, not shipped behavior.

License disposition: copy when allowed

Read the license at the exact studied revision and check per-file/NOTICE/provenance boundaries. Classify every candidate before implementation:

• DIRECT-PORT: copying/modification is permitted and obligations fit. Prefer copying the smallest coherent implementation or test, preserving notices and source path@sha, then adapt.
• ADAPT: reuse is permitted but fak interfaces, dependencies, or constraints require material changes. Identify direct versus rewritten portions and retain attribution.
• INSPIRE-ONLY: terms are absent, unclear, incompatible, proprietary, or behavior-only. Build independently; do not copy expressive code, tests, comments, or assets.
• DO-NOT-USE: provenance or terms are unsafe; exclude and record why.

Do not default to inspire-only because clean-room rewriting feels cleaner. Public visibility also does not grant permission. When obligations are ambiguous, use INSPIRE-ONLY or seek review.

Expansive candidate extraction

Extract all of these before ranking:

• direct mechanisms: algorithms, schemas, tests, UX, operations, and documentation;
• negative knowledge: reverts, rejected proposals, recurring issue failures, regressions, reviews;
• emerging direction: open PRs, issues, RFCs, roadmaps, TODOs, and design sketches, marked proposed;
• Spirit extensions: infer the broader principle and adjacent fak applications, using source fact -> inferred principle -> fak opportunity -> disconfirming check;
• combinations across independent sources that produce a stronger design.

Be expansive in discovery and conservative in claims. A promising unimplemented idea is a valid INFERENCE when paired with a cheap experiment/falsifier; it is not parity evidence.

Bounded-superset portfolio rule

The target is not "copy the winner" and not "accumulate every feature." It is a bounded capability superset: within fak's declared scope and support budget, users should be able to trust that fak carries the strongest reasonable industry default and preserves materially useful alternatives for cohorts whose constraints differ. fak is egoless about where those capabilities originated. Its modular leaf/adapter/integration boundaries are an advantage: a useful alternative need not displace the default or contaminate the kernel core.

For every witnessed capability, record one portfolio disposition:

Disposition	Use when	Required form
DEFAULT	strongest net-true choice for the common supported case	integrated, documented default with a witness against the real alternative
OPTIONAL-MODULE	useful for a named user/job/constraint but not the broad default	isolated leaf, adapter, policy, backend, or integration; explicit opt-in and support owner
RECIPE	useful and supportable, but too narrow or environment-specific to ship as maintained code	tested composition/integration guide with prerequisites and dated witness
WATCH	promising, moment-in-time, immature, or evidence is not strong enough to support yet	dated source + review trigger; no shipped claim
EXCLUDE	outside scope, unsafe, license-incompatible, operationally unaffordable, or genuinely dominated	named reason and the evidence/disconfirming condition that could reopen it

DEFAULT is not the only successful outcome. Do not reject a capability merely because a different technique wins overall, is newer, or is already fak's default. Ask whether a real supported cohort still benefits under a constraint such as hardware, provider, latency, quality, privacy, deployment topology, compatibility, cost, or operator preference. If yes, prefer an OPTIONAL-MODULE or RECIPE seam over deletion. Conversely, age, popularity, or "someone might want it" is not enough: an obviously superseded approach with no surviving cohort goes to EXCLUDE, and a fast-moving snapshot goes to WATCH until revalidated.

Each non-excluded row must name: capability axis; user/job/constraint served; observed evidence and date; relationship to the default; proposed modular seam; incremental build, test, security, documentation, and maintenance cost; owner or review trigger; and a witness that would disconfirm usefulness. This is the reasonable-coverage budget. Once marginal support cost exceeds witnessed user value, stop expanding and register the omission instead of boiling the ocean.

A study is coverage-complete only when it reports both:

1. Default frontier — where fak's common-case default should lead or change.
2. Coverage frontier — useful supported cohorts still absent even though the default may already be best overall.

Required completion evidence

In addition to the PRESENT/PARTIAL/ABSENT self-query pass below, completion requires a coverage checklist, dated source ledger, license disposition, candidate matrix (fact versus inference and shipped versus proposed), exact fak seam, and either shipped proof or contract-ready filed work. Prefer shipping a safe in-scope minimal spine now over reflexively creating backlog. A long link list is not exhaustive research: state what each source changed in the conclusion.

Why this skill exists

fak researches the outward field well — the docs/notes/RESEARCH-* corpus, industry-score, idea-scout, sota-check all point outward. But applying a field idea inward has a silent failure mode: an agent reads "Cognee does GraphRAG" or "Zep has bi-temporal memory" and files "fak should add graph memory" without first asking fak whether it already has it — so the tracker accretes gaps fak already closed, or gaps described one abstraction away from the real seam. The research was outward-complete but the witness step was manual and skipped.

The law, in one line: the default answer to "does fak already have this field-standard capability?" is ask fak, don't assume — dogfood the self-query surface to witness present / partial / absent, then file only the witnessed gaps, each grounded in a seam.

This is the loop that produced #3161 / #3162 / #3163 (edge-aware query, retrieval-eval, freshness rung) under epic #1494: three retrieval-quality gaps borrowed from Cognee/Zep, LongMemEval/LOCOMO, and Zep/Mem0 — each witnessed by querying fak_feature_query against fak's own internal/selfquery before filing, each grounded at internal/selfquery/selfquery.go (the flat lexical ranker at :566). See docs/notes/CONCEPT-FIELD-BORROW-QUERY-QUALITY-2026-07-08.md for that worked instance.

How this differs from its siblings (do not duplicate them)

Skill / tool	Direction	Mechanism	Files issues?	Dogfoods the self-query witness?
sota-check	inward, kernels only	fak sota <op> prior-art matrix	no	no
industry-score	outward	scorecard: coverage + parity-debt over a taxonomy	no	no
idea-scout (tools/idea_scout.py)	outward, automated	arXiv/GitHub scan, dedup vs existing issues (seen-cache · body-stamp · title-Jaccard)	yes (triage queue)	no (issue-vs-issue only, never capability-vs-codebase)
field-borrow (this)	outward→inward	dogfood fak_feature_query to witness the gap, then file epic-anchored	yes (grounded, under the right epic)	yes — this is the point

field-borrow composes with all three: it can be the human-in-the-loop pass over an idea-scout hit, it feeds witnessed coverage rows to industry-score, and once a spine ships it hands off to spine-fanout.

Durable study receipt — query first, record the disposition last

Before acquiring the external source, run fak study search "<source-or-capability>" --limit 20. Use a hit to choose and report extend, recheck, or supersede rather than duplicating the study. Missing or unavailable storage degrades explicitly: report durable study memory unavailable: <error>, continue with bounded local evidence, and never call that evidence persisted.

After the PRESENT/PARTIAL/ABSENT witness and disposition exist, write a pinned fak-study/1 record with fak study add --file <record.json>. Put the returned study_... ID in every downstream GitHub issue body. Verified implementation outcomes append through a new receipt with an outcome and supersedes link; they do not rewrite or model-promote the original decision.

Promotion evidence: a fresh invocation discovers the candidate through bounded search and returns the same record ID. Demote or retire this seam if it does not prevent duplicate study or if storage failures can masquerade as persistence. Invalidating assumption: source names and capability terms provide enough lexical signal for bounded rediscovery.

The pass

1 — Name the source and the capability axis (dated)

Pick ONE capability from a named external system or a dated source: an agent-memory product (Letta/MemGPT, Mem0, Zep/Graphiti, Cognee, Supermemory), a serving system (vLLM/SGLang/TensorRT-LLM), a competitor feature, a benchmark (LongMemEval, LOCOMO), or a row from the RESEARCH-* / industry field scans. Write it down with the source, so the borrow is falsifiable: "Zep/Graphiti — bi-temporal edges: facts carry validity windows; a newer fact invalidates the old one." One capability per pass; do not batch.

2 — Dogfood the self-query WITNESS (the heart of this skill)

Ask fak, three ways, whether it already has the capability — do not reason about it from memory:

• fak_feature_query (MCP) / fak capabilities <intent> — intent → ranked capability cards (name, summary, witness content-address, the call to make).
• fak index docs|leaves|verbs|claims <terms> — the dev self-index over docs, packages, CLI verbs, and the CLAIMS ledger.
• Also a plain Grep for the concept's obvious symbol, to catch a capability the lexical ranker missed (see Honest limits).

Classify the result, and paste the top cards as the witness:

• PRESENT — a card / verb / leaf directly does it. Read it and confirm it truly does (not just a name collision). PRESENT is a valid, complete, good outcome — "fak already has this, here is the card" ends the pass; do not file.
• PARTIAL — an adjacent surface exists but not this capability (e.g. fak_index_freshness covers index↔tree drift but not semantic supersession).
• ABSENT — the query surfaces nothing on-point. An ABSENT claim must show the query that returned nothing on-point — that null result is the falsifiable witness.

3 — Ground the PARTIAL/ABSENT in a seam (file:line)

The capability cards point at the code. Find the exact file:line the capability would touch and quote one dogfood result as the in-issue evidence — e.g. the flat lexical ranker score() at internal/selfquery/selfquery.go:566, or the FeatureCard struct at :37 that carries no freshness/edge field. No file:line seam, no issue — a gap you cannot locate is not ready to file; keep witnessing until you can point at the code.

4 — Dedup, then file grounded (under the right epic)

Search existing issues and the natural parent epic before filing (avoid re-filing what idea-scout or a human already opened). File under the epic with, in order:

1. the pain, in fak's terms, quoting the seam from step 3;
2. the named external inspiration (dated — a fabricated "system X does Y" is the exact citation failure dos_citation_resolve exists to catch);
3. the dogfood witness from step 2 (the query + what it returned);
4. a concrete first checkable step (the smallest thing that proves the gap is real and the fix is buildable);
5. honest fences (deterministic / advisory / read-only where they apply).

Set milestone + labels at creation. On this host, run gh via PowerShell or the Bash tool deliberately (quote bodies through --body-file, not inline heredocs that the shell mangles).

5 — Register the trail (or it lives only in a transcript)

Record the instance in a dated docs/notes/CONCEPT-<topic>-<date>.md: source → witness → seam → filed issues, with a Companions: block. Add its INDEX.md line in the Notes & research section (an unindexed dated note is an orphan fak index freshness flags). Link the children from the parent epic. This registration — not the issues alone — is what makes the research path durable.

6 — (optional) Feed the map

A witnessed PRESENT/PARTIAL/ABSENT is a coverage row industry-score can absorb; a genuinely novel, spine-shaped gap can seed spine-fanout once a working spine ships.

What "done" proves

• Every filed gap carries a dogfood witness (the query + its top cards), a file:line seam, a named dated external source, and a first checkable step.
• No gap was filed that fak already ships (step 2 caught the PRESENT cases).
• The instance is registered: a dated docs/notes entry, its INDEX.md line, and the epic links its children. python tools/... freshness / fak index freshness reads clean for the new note.

The anti-gaming rule (specific to this surface)

Never file a capability gap you did not dogfood-witness, and never mark ABSENT without the null query. The witness is the falsifiable record — the way sota-check's Prior-art: trailer is. Two failure modes this rule kills:

• Assumed-absent. Filing "fak lacks X" from memory when fak_feature_query would have returned the card. The fix is the query, pasted.
• Fabricated borrow. "Zep does bi-temporal invalidation" when it does not, or citing a system/paper you did not read. Name the source, dated; if you could find no prior art, say that so the next person can disprove it.

PRESENT is not a failed pass — a witnessed "we already have this" is a real result.

Where this misleads / honest limits

• The self-query score is lexical. rankCards/score() (internal/selfquery/selfquery.go:540,566) is strings.Contains substring matching over name/tags/ref/summary — a poorly-phrased query can miss a card fak does have, producing a false-ABSENT. Read the top cards, vary the phrasing, and cross-check with a raw Grep before trusting an ABSENT. (This limit is itself issue #3162 — the ranker is ungraded.)
• ABSENT means "fak's own index doesn't surface it", not "it doesn't exist." The index can be stale or the capability can live under a name you didn't guess.
• The witness is a snapshot. A card added tomorrow changes the verdict (the freshness problem is issue #3163). Re-witness before acting on an old pass.
• Composes with, does not replace: idea-scout (automated outward feeder), industry-score (the competitive coverage map), spine-fanout (post-spine fan-out), sota-check (kernel prior-art). If the capability is a compute kernel, use sota-check instead — this pass is for product / agent / memory / serving capabilities.

When to run this

• Reading a RESEARCH-* / SOTA / competitor note and wondering "do we already have this?"
• Before filing any "fak should add X" capability-gap issue.
• After a competitor or a paper ships a capability worth borrowing.
• On a /loop cadence over the docs/notes/RESEARCH-* corpus, to convert inert research into witnessed, grounded, epic-anchored backlog — the inward, human-curated complement to the daily idea-scout.