Imported from khoshov/integration (caveman-main/shrink/AGENTS.md). Install upstream with npx skills add khoshov/integration --skill shrink. Copyright stays with the author.

shrink — caveman-shrink, the tool-catalog compressor (commercial Go core + MIT launcher)

Compress MCP/OpenAI tool definitions before they fill the context window. A thin Go wrapper over the engine's toolschema compressor: it drops annotation metadata (examples, titles, $comment, $schema) and reduces long descriptions to their lead plus every constraint-bearing sentence. It keeps every selection token (tool/parameter names, types, enums, required) and argument-construction value (default, const, $ref targets) byte-for-byte. Everything is inferred.

Layout

• shrink.go — the library: Shrink (catalog → compressed, fail-open S4 transform, durable-CCR-backed), Recover (handle → original bytes), Lint (per-tool inferred token reductions), SelectionProfile (the structural surface — what must survive). WithStore/WithStorePath select recovery storage; default is CAVEMAN_CCR_DB / ~/.caveman/ccr.db.
• cmd/caveman-shrink/ — the CLI: caveman-shrink / shrink (stdin→stdout), lint <file>, and recover <handle>.
• bin/caveman-shrink.mjs + package.json — the npx caveman-shrink launcher around the prebuilt binary.

Two correctness boundaries

SelectionProfile(input) == SelectionProfile(Shrink(input).Output) always. This proves the structural selection surface (names/params/enums/required) survives byte-for-byte. It does not prove the model selects the same tool: descriptions are model-visible and long descriptions are lossy. Behavioral selection equivalence requires model-eval fixtures; keep results inferred.

Selection alone does not guarantee valid arguments. Short descriptions stay whole; long ones keep the lead plus every recognised constraint sentence (must/cannot/required/bounds/format/ ISO/RFC/absolute/etc.). default, const, and internal $ref targets survive. Golden and adversarial conformance tests lock these construction surfaces; over-keep is safer than a retry.

Conventions

• Build/test: make product-build PRODUCT=shrink / make product-test PRODUCT=shrink.
• The structural compressor lives in the engine (compressors/toolschema.go); shrink reuses it, never forks it.
• This is the dedicated product surface for the toolschema compressor. Engine API/CLI callers can also force it locally. Managed-gateway adapters keep tool arrays in the frozen prompt-cache prefix and never hand them to it; gateway's separate S2 tool-search/deferral path is not compression. Local reductions stay inferred. A future billed route for this transform needs cache-versus-schema cost proof, stable byte-identical prefix output, and an eval gate.

Gotchas (honesty invariants)

• S4 lossy, fail-open — successful compression changes model-visible bytes; malformed/incompressible catalogs pass through unchanged (ratio:0, no handle).
• inferred-only — token counts are estimates via the engine's offline counter; never verified, never re-projected.
• reversible for real — a compressing shrink commits the exact original to the durable shared CCR store before returning a handle. A separate process resolves it through Recover / caveman-shrink recover; failure to open storage makes library Shrink return an error, while the CLI catches that error and forwards the original bytes with no handle.

See ../../CLAUDE.md (root) · ../engine/CLAUDE.md