feat: generate brain tools skill from OpenAPI; rename db-yaml to postgres (#21)

Cursor skills stay in lockstep with serve handlers. CI checks every bin/
path named in SKILL.md exists.

AGENTS.md

@@ -77,11 +77,15 @@ bin/brain/index.go --rebuild                                            # rebuil
 ## Tools
 
 ```bash
-bin/facts/audit ["self"|"facts"|"info"|"stale"]   # 2-source + staleness gate
+bin/facts/audit.go ["self"|"facts"|"info"|"stale"]  # 2-source + staleness gate
-bin/facts/crm [--dry-run]                         # proof person↔company/company↔project (ooCRM × corpus SoT)
+bin/facts/crm.go [--dry-run]                       # proof person↔company/company↔project (ooCRM × corpus SoT)
 bin/kb/search "query" [--repo X]                  # deprecated wrapper → bin/brain/search.go
 bin/brain/search.go "query" [--root facts|info]   # deduction search → YAML
-bin/brain/get.go <id> [--body]
+bin/brain/search.go "query" --no-web              # local graph only
+bin/brain/get.go <id> [--body] [--json]          # Go read; Python bin/kb/get CI fallback
+bin/brain/stats.go [--json]
+bin/brain/eval.go [--json]                       # recall@5; questions in internal/brain/rank
+bin/brain/serve.go                               # HTTP :8630; GET /openapi.json POST /mcp
 bin/markdown/import.go [dir]                      # mistune leaves → YAML
 bin/git/import.go [REPO] [--json] [--limit N]     # go-git history → commit leafs
 bin/web/search.go "query" [--json]                # SearXNG; throttled ≠ absence

PLAN.md

@@ -29,7 +29,7 @@ detective method: **a fact needs ≥2 independent sources or it is
 | D3 | web search | Go client `bin/web/search.go` (`internal/websearch`). SearXNG URL is config (`BRAIN_SEARCH_URL`). Optional Compose profile `searxng` (sanitized settings). Do not run a second copy on a host that already has one. Empty/`throttled` ≠ “nothing exists”. |
 | D4 | embeddings | **model2vec** `minishlab/potion-multilingual-128M` instead of embeddinggemma. |
 | D5 | parser | **mistune** for MD → leaf extraction (duckdb-md documented as future optional SQL/export layer, not v1). |
-| D6 | graph engine | **LadybugDB**. Go is the service (`bin/brain/search.go`, `bin/brain/serve.go` in-process, `internal/brain`); Python remains for index/write until the Go write path is safe. |
+| D6 | graph engine | **LadybugDB**. Go is the service (`bin/brain/search.go`, `bin/brain/serve.go` in-process, `internal/brain`). Read path (`get.go` / `stats.go` / `eval.go`) is Go + cgo. Python `bin/kb/{get,stats,eval}` is the CI fallback (GitHub runners have no ladybug cgo). Index/write stays Python until the Go write path is safe. |
 | D7 | db access | `db-yaml`/`psql-yq`-style, read-only, YAML out. OnlyOffice Postgres via SSH tunnel (`127.0.0.1:5433`). |
 | D8 | evidence | detective method: ≥2 independent sources or `(not confirmed)`. Auto-pair docker ps × compose × ssh-config × docs. |
 | D9 | facts/goal model | Who / What / How / Where / When + evidence + confidence on every edge. |
@@ -40,9 +40,10 @@ detective method: **a fact needs ≥2 independent sources or it is
 | D14 | tooling style | `bin/{subject}/{method}.go` shebang (e.g. `bin/brain/search.go`). Shared code in `internal/`. One root `go.mod` + `go.work`. No `bin/*/main.go`, no nested modules. |
 | D15 | repo | Gitea [`eSlider/2dph`](https://git.produktor.io/eSlider/2dph) is origin + [issues](https://git.produktor.io/eSlider/2dph/issues). GitHub `eSlider/2dph` is the public clone (PRs + Actions CI). No direct `main` pushes. TDD → PR → CI green → merge. |
 | D16 | contradictions | ≥2 yes vs ≥2 no → unrelated sources conflict → hypothesis → `(not confirmed)`. Resolution (authority, staleness adjudication) = **v2**, tracked as open question. |
-| D17 | assertion gate | Fact-check every *claim* (facts → info → live sources → web), not every edit. Missing graph ≠ “does not exist”. |
+| D17 | assertion gate | Fact-check every *claim* (facts → info → live → web), not every edit. `bin/brain/search.go` adds a `web` block when there is no facts hit (`throttled`/`skipped`/`refused` ≠ absence). `--root` and `--no-web` stay local. Missing graph ≠ “does not exist”. |
 | D18 | reasoner | Pluggable OpenAI-compatible URL. RAM: Qwen3.5-9B. Quality: Bonsai-27B or Qwen3.6-27B. No official Qwen3.6-9B. |
 | D19 | git history | [go-git](https://github.com/go-git/go-git) via `bin/git/import.go`. No subprocess of the git binary. Conversion prints commit leafs; brain write is `bin/brain/index.go`. |
+| D20 | agent API | OpenAPI + MCP are generated from the same `internal/httpapi.Ops` table as `bin/brain/serve.go` handlers. `GET /openapi.json`, `POST /mcp` (JSON-RPC tools/list + tools/call). Tool names match OpenAPI paths (`search`/`get`/`stats`/`audit`). |
 
 ## Architecture
 
@@ -50,15 +51,15 @@ detective method: **a fact needs ≥2 independent sources or it is
 2dph/
   PLAN.md / AGENTS.md
   docs/                     published docs (this conversation → docs/ as md)
-  skills/                   in-project skills (web-search, db-yaml, brain, diataxis-docs)
+  skills/                   in-project skills (web-search, postgres, brain, diataxis-docs)
   bin/
-    facts/extract           auto-pair 2 sources → lexicon yaml + graph
+    facts/extract.go audit.go crm.go  # D14 shebang; Python implementation
-    facts/audit             ["self"|"facts"|"info"|"stale"] 2-source + staleness gate
     kb/index                Python write path (called by bin/brain/index.go)
     brain/index.go          rebuild FTS + HNSW (incl. --with-mail)
-    brain/get.go stats.go eval.go watch.go
+    brain/get.go stats.go eval.go  # Go read (cgo); Python bin/kb/* CI fallback
+    brain/watch.go
     brain/search.go         deduction: facts → info → web-search
-    brain/serve.go          HTTP API in-process (internal/httpapi + internal/brain)
+    brain/serve.go          HTTP API in-process + OpenAPI/MCP (D20)
     mail/import.go          JSON → markdown (no brain write)
     markdown/import.go      mistune leaves
     postgres/query.go       read-only YAML (wraps bin/db/psql-yq)
@@ -132,8 +133,10 @@ Common props on every node/edge: `root`, `confidence`, `evidence[]`, `how`,
 1. go vet + go test ./... (root module; packages without ladybug cgo)
 2. `go test ./internal/brain/rank` (cgo-free ranking + flag parser)
 3. python -m unittest discover -s bin/tools (includes published-docs SoT)
-4. bin/facts/audit self  (lexicon internal consistency)
+4. `bin/facts/audit self` (lexicon internal consistency; `bin/facts/audit.go` is the D14 wrapper)
-5. bin/brain/eval.go       (recall@5 ≥ 0.95, gates index regressions)
+5. `bin/kb/eval` (recall@5 ≥ 0.95). Local SoT is `bin/brain/eval.go`; CI uses
+   the Python twin until the runner has ladybug cgo. Questions live in
+   `internal/brain/rank`.
 6. md-docs build/lint if docs tooling arrives.
 
 Feedback loop: every commit → PR → CI → green/gate → merge. Same discipline as
@@ -143,7 +146,7 @@ Feedback loop: every commit → PR → CI → green/gate → merge. Same discipl
 
 1. scaffold repo (:done after this file + AGENTS.md + .gitignore + ci)
 2. gh repo create eSlider/2dph --private + initial commit + CI
-3. vendored skill integration (web-search, db-yaml, brain, diataxis-docs) — no remote links
+3. vendored skill integration (web-search, postgres, brain, diataxis-docs) — no remote links
 4. .venv: ladybug + model2vec + mistune
 5. schema + tools with TDD (kb + md + facts + brain)
 6. ~/.config/brain config

README.md

@@ -28,8 +28,8 @@ graph TB
     end
 
     subgraph dph["2dph tools"]
-        EX["bin/facts/extract<br/>2-source pairing"]
+        EX["bin/facts/extract.go<br/>2-source pairing"]
-        AU["bin/facts/audit<br/>confidence + staleness"]
+        AU["bin/facts/audit.go<br/>confidence + staleness"]
         IDX["bin/brain/index.go<br/>chunk + embed"]
         MD["bin/markdown/import.go<br/>mistune leaves"]
         SR["bin/brain/search.go<br/>deduction"]
@@ -85,9 +85,10 @@ fact; conflicting sources or a single source → `hypothesis` → `(not confirme
 ## Deduction search
 
 ```bash
-bin/brain/search.go "Matrix federation over HTTPS"   # facts → info → web-search
+bin/brain/search.go "Matrix federation over HTTPS"   # facts → info → web
 bin/brain/search.go "onlyoffice postgres" --root facts
 bin/brain/search.go "where is cs-lexicon" --json | yq '.'
+bin/brain/search.go "upstream flag" --no-web         # local graph only
 bin/brain/get.go <id> --body                         # full chunk on demand
 bin/brain/stats.go                                   # index health
 bin/brain/eval.go                                    # recall@5 gate
@@ -125,7 +126,8 @@ bin/brain/search.go "invoice from last week"                            # same s
 
 - **LadybugDB** — single `var/kb.lbug`, Cypher property graph, HNSW + BM25
   in one engine, embedded (no server), ACID, read-only-safe for concurrent
-  readers. **Never `DROP INDEX` FTS/VECTOR** on Ladybug 0.19: DROP leaves
+  readers. Read tools (`get` / `stats` / `eval`) are Go + cgo; Python
+  `bin/kb/{get,stats,eval}` is the CI fallback. **Never `DROP INDEX` FTS/VECTOR** on Ladybug 0.19: DROP leaves
   ghost catalog tables (`_0_Leaf_vec_UPPER`) so recreate fails while
   `SHOW_INDEXES` omits HNSW. Fresh indexes = delete `var/kb.lbug` +
   `bin/brain/index.go --rebuild`. Use `ensure_indexes()` after upserts.
@@ -139,14 +141,14 @@ bin/brain/search.go "invoice from last week"                            # same s
 `bin/{subject}/{method}.go` — self-describing: shebang on line 1, usage comment
 from line 2. Shared code in `internal/`. YAML default output, `--json` for
 machines. Tests gate every commit. HTTP: `bin/brain/serve.go` calls
-`internal/brain` in-process (`/health` `/search` `/get` `/stats` `/audit` `/ingest`).
+`internal/brain` in-process (`/health` `/search` `/get` `/stats` `/audit` `/ingest` `/openapi.json` `/mcp`).
 
 ## Development
 
 ```bash
 uv venv .venv                                  # Python 3.12, uv-managed
 uv pip install -r requirements.lock.txt        # pinned toolchain
-bin/facts/audit self                           # lexicon consistency gate
+bin/facts/audit.go self                        # lexicon consistency gate
 go test ./... && python -m unittest discover -s bin/tools -t .
 ```
 
@@ -164,7 +166,7 @@ docker compose up brain-watch                  # auto re-index on change
 - [go-second-brain](https://github.com/eSlider/go-second-brain) — the earlier
   Neo4j + Qdrant + Matrix RAG brain
 - [agent-skills](https://github.com/eSlider/agent-skills) — upstream
-  skills (`web-search`, `db-yaml`, …) that 2dph integrates
+  skills (`web-search`, `postgres`, …) that 2dph integrates
 - detective method — the two-source method
 
 Work board (issues): [git.produktor.io/eSlider/2dph/issues](https://git.produktor.io/eSlider/2dph/issues).

bin/brain/eval.go

@@ -1,20 +1,22 @@
-//usr/bin/env go run -tags=brain_eval "$0" "$@"; exit
+//usr/bin/env go run -tags=system_ladybug,brain_eval "$0" "$@"; exit
-//go:build brain_eval
+//go:build cgo && system_ladybug && brain_eval
 //
 // bin/brain/eval.go - recall@5 gate.
 //
 //	./bin/brain/eval.go
 //	./bin/brain/eval.go --json
 //
+// Needs CGO + libladybug. Python bin/kb/eval is the CI fallback (no cgo).
+// Control questions live in internal/brain/rank (cgo-free).
 // NOTE: never run `gofmt -w` on this file — it breaks the shebang.
 package main
 
 import (
 	"os"
 
-	"github.com/eSlider/2dph/internal/cmdbin"
+	"github.com/eSlider/2dph/internal/brain"
 )
 
 func main() {
-	os.Exit(cmdbin.ExecFile("bin/kb/eval", os.Args[1:]))
+	os.Exit(brain.MainEval(os.Args[1:]))
 }

bin/brain/get.go

@@ -1,20 +1,22 @@
-//usr/bin/env go run -tags=brain_get "$0" "$@"; exit
+//usr/bin/env go run -tags=system_ladybug,brain_get "$0" "$@"; exit
-//go:build brain_get
+//go:build cgo && system_ladybug && brain_get
 //
 // bin/brain/get.go - read one leaf by id.
 //
 //	./bin/brain/get.go <id>
 //	./bin/brain/get.go <id> --body
+//	./bin/brain/get.go <id> --json
 //
+// Needs CGO + libladybug. Python bin/kb/get is the CI fallback (no cgo).
 // NOTE: never run `gofmt -w` on this file — it breaks the shebang.
 package main
 
 import (
 	"os"
 
-	"github.com/eSlider/2dph/internal/cmdbin"
+	"github.com/eSlider/2dph/internal/brain"
 )
 
 func main() {
-	os.Exit(cmdbin.ExecFile("bin/kb/get", os.Args[1:]))
+	os.Exit(brain.MainGet(os.Args[1:]))
 }

bin/brain/search.go

@@ -3,7 +3,7 @@
 //
 // bin/brain/search.go - deduction search over the 2dph brain.
 //
-//	./bin/brain/search.go "query" [--root facts|info] [--repo P] [-n N] [--json]
+//	./bin/brain/search.go "query" [--root facts|info] [--repo P] [-n N] [--json] [--no-web]
 //	./bin/brain/search.go serve [port]
 //	./bin/brain/search.go --list-model
 //

bin/brain/serve.go

@@ -6,6 +6,9 @@
 //	KB_ROOT=/path/to/2dph ./bin/brain/serve.go
 //	KB_WORKERS=4 KB_PORT=8630 ./bin/brain/serve.go
 //
+//	GET  /openapi.json  same Ops table as the handlers
+//	POST /mcp           JSON-RPC tools/list + tools/call
+//
 // Needs CGO + libladybug (same as bin/brain/search.go).
 // NOTE: never run `gofmt -w` on this file — it breaks the shebang.
 package main

bin/brain/stats.go

@@ -1,20 +1,21 @@
-//usr/bin/env go run -tags=brain_stats "$0" "$@"; exit
+//usr/bin/env go run -tags=system_ladybug,brain_stats "$0" "$@"; exit
-//go:build brain_stats
+//go:build cgo && system_ladybug && brain_stats
 //
 // bin/brain/stats.go - index health.
 //
 //	./bin/brain/stats.go
 //	./bin/brain/stats.go --json
 //
+// Needs CGO + libladybug. Python bin/kb/stats is the CI fallback (no cgo).
 // NOTE: never run `gofmt -w` on this file — it breaks the shebang.
 package main
 
 import (
 	"os"
 
-	"github.com/eSlider/2dph/internal/cmdbin"
+	"github.com/eSlider/2dph/internal/brain"
 )
 
 func main() {
-	os.Exit(cmdbin.ExecFile("bin/kb/stats", os.Args[1:]))
+	os.Exit(brain.MainStats(os.Args[1:]))
 }

bin/facts/audit.go

@@ -0,0 +1,21 @@
+//usr/bin/env go run -tags=facts_audit "$0" "$@"; exit
+//go:build facts_audit
+//
+// bin/facts/audit.go - 2-source + lexicon checks.
+//
+//	./bin/facts/audit.go self
+//	./bin/facts/audit.go db
+//
+// Python bin/facts/audit is the implementation (CI runs it directly).
+// NOTE: never run `gofmt -w` on this file — it breaks the shebang.
+package main
+
+import (
+	"os"
+
+	"github.com/eSlider/2dph/internal/cmdbin"
+)
+
+func main() {
+	os.Exit(cmdbin.ExecFile("bin/facts/audit", os.Args[1:]))
+}

bin/facts/crm.go

@@ -0,0 +1,20 @@
+//usr/bin/env go run -tags=facts_crm "$0" "$@"; exit
+//go:build facts_crm
+//
+// bin/facts/crm.go - prove person↔company / company↔project (ooCRM × corpus).
+//
+//	./bin/facts/crm.go [--dry-run] [--mismatches]
+//
+// Python bin/facts/crm is the implementation. Graph write stays Python.
+// NOTE: never run `gofmt -w` on this file — it breaks the shebang.
+package main
+
+import (
+	"os"
+
+	"github.com/eSlider/2dph/internal/cmdbin"
+)
+
+func main() {
+	os.Exit(cmdbin.ExecFile("bin/facts/crm", os.Args[1:]))
+}

bin/facts/extract.go

@@ -0,0 +1,20 @@
+//usr/bin/env go run -tags=facts_extract "$0" "$@"; exit
+//go:build facts_extract
+//
+// bin/facts/extract.go - acquire confirmed facts (2-source each).
+//
+//	./bin/facts/extract.go [--json] [--dry-run]
+//
+// Python bin/facts/extract is the implementation. Graph write stays Python.
+// NOTE: never run `gofmt -w` on this file — it breaks the shebang.
+package main
+
+import (
+	"os"
+
+	"github.com/eSlider/2dph/internal/cmdbin"
+)
+
+func main() {
+	os.Exit(cmdbin.ExecFile("bin/facts/extract", os.Args[1:]))
+}

bin/tools/test_bin_layout.py

@@ -77,6 +77,44 @@ class BinLayoutTest(unittest.TestCase):
         for method in ("index.go", "get.go", "stats.go", "eval.go", "watch.go"):
             self._assert_shebang(f"bin/brain/{method}")
 
+    def test_brain_get_stats_eval_are_not_python_exec(self) -> None:
+        for method in ("get.go", "stats.go", "eval.go"):
+            text = (ROOT / "bin" / "brain" / method).read_text()
+            self.assertNotIn(
+                "ExecFile",
+                text,
+                f"bin/brain/{method} must call internal/brain, not ExecFile Python",
+            )
+            self.assertNotIn(
+                "cmdbin",
+                text,
+                f"bin/brain/{method} must not import internal/cmdbin",
+            )
+            self.assertIn(
+                "system_ladybug",
+                text.splitlines()[0],
+                f"bin/brain/{method} shebang must pass -tags=system_ladybug",
+            )
+            self.assertIn(
+                "github.com/eSlider/2dph/internal/brain",
+                text,
+            )
+
+    def test_eval_control_questions_live_in_rank(self) -> None:
+        rank = (ROOT / "internal" / "brain" / "rank" / "evalq.go").read_text()
+        py = (ROOT / "bin" / "kb" / "eval").read_text()
+        for frag in ("BM25", "DevOps", "LadybugDB"):
+            self.assertIn(frag, rank)
+            self.assertIn(frag, py)
+        self.assertIn("0.95", rank)
+
+    def test_facts_methods_are_shebangs(self) -> None:
+        for method in ("audit.go", "extract.go", "crm.go"):
+            self._assert_shebang(f"bin/facts/{method}")
+            text = (ROOT / "bin" / "facts" / method).read_text()
+            self.assertIn("cmdbin.ExecFile", text)
+            self.assertIn(f"bin/facts/{method.removesuffix('.go')}", text)
+
     def test_mail_import_is_shebang_not_brain_write(self) -> None:
         self._assert_shebang("bin/mail/import.go")
         index_mail = (ROOT / "bin" / "mail" / "index_mail").read_text()

bin/tools/test_published_docs.py

@@ -59,6 +59,31 @@ class PublishedDocsTest(unittest.TestCase):
         self.assertNotIn("password", settings.lower())
         self.assertIn("json", settings)
 
+    def test_readme_read_path_is_go(self) -> None:
+        plan = (ROOT / "PLAN.md").read_text()
+        self.assertIn("get.go", plan)
+        self.assertIn("CI fallback", plan)
+        design = (ROOT / "docs" / "design.md").read_text()
+        self.assertIn("internal/brain/rank", design)
+        self.assertIn("They do not exec Python", design)
+
+    def test_openapi_mcp_from_same_handlers(self) -> None:
+        plan = (ROOT / "PLAN.md").read_text()
+        self.assertIn("D20", plan)
+        self.assertIn("/openapi.json", (ROOT / "README.md").read_text())
+        self.assertIn("/mcp", (ROOT / "README.md").read_text())
+        skill = (ROOT / "skills" / "brain" / "SKILL.md").read_text()
+        self.assertIn("/mcp", skill)
+        self.assertFalse((ROOT / "skills" / "db-yaml").exists())
+        self.assertTrue((ROOT / "skills" / "postgres" / "SKILL.md").is_file())
+
+    def test_readme_search_escalates_web(self) -> None:
+        text = (ROOT / "README.md").read_text()
+        self.assertIn("--no-web", text)
+        self.assertIn("D17", (ROOT / "PLAN.md").read_text())
+        skill = (ROOT / "skills" / "brain" / "SKILL.md").read_text()
+        self.assertIn("`web` block", skill)
+
     def test_docs_do_not_claim_hop_walks(self) -> None:
         paths = [
             ROOT / "README.md",

bin/tools/test_skills.py

@@ -0,0 +1,39 @@
+"""Skills must name live commands; every bin/ path in SKILL.md must exist."""
+from __future__ import annotations
+
+import re
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+BIN_PATH = re.compile(r"(bin/[A-Za-z0-9_./-]+)")
+
+
+class SkillsTest(unittest.TestCase):
+    def test_db_yaml_renamed_to_postgres(self) -> None:
+        self.assertFalse(
+            (ROOT / "skills" / "db-yaml").exists(),
+            "skills/db-yaml must be skills/postgres",
+        )
+        self.assertTrue((ROOT / "skills" / "postgres" / "SKILL.md").is_file())
+        text = (ROOT / "skills" / "postgres" / "SKILL.md").read_text()
+        self.assertIn("bin/postgres/query.go", text)
+        self.assertNotIn("search.ops.io", text)
+
+    def test_every_bin_path_in_skills_exists(self) -> None:
+        missing: list[str] = []
+        for path in (ROOT / "skills").rglob("SKILL.md"):
+            text = path.read_text()
+            for m in BIN_PATH.finditer(text):
+                rel = m.group(1).rstrip(")`.,;")
+                candidate = ROOT / rel
+                if not candidate.exists():
+                    missing.append(f"{path.relative_to(ROOT)}: {rel}")
+        self.assertEqual(missing, [], "skill bin paths must exist")
+
+    def test_brain_skill_lists_generated_tools(self) -> None:
+        tools = (ROOT / "skills" / "brain" / "tools.md").read_text()
+        skill = (ROOT / "skills" / "brain" / "SKILL.md").read_text()
+        self.assertIn("tools.md", skill)
+        for name in ("search", "get", "stats", "audit"):
+            self.assertIn(f"`{name}`", tools)

docs/design.md

@@ -21,7 +21,8 @@ bin/brain/search.go "question"
   1. facts root   — confirmed answers only   → return with evidence links
   2. info  root   — supporting narrative     → snippets, marked (not confirmed)
   3. web-search   — second independent source → upgrade hypothesis to confirmed
-     (`bin/web/search.go`; status `throttled` is not evidence of absence)
+     (`web` block from `bin/web/search.go` when no facts hit; status `throttled`
+     is not evidence of absence; `--no-web` / `--root` skip it)
 ```
 
 `--hop` is not implemented yet (needs File/FROM_FILE edges). The flag is an
@@ -61,3 +62,18 @@ corpus HEAD.
 
 Confirmed = A×B or B×C agreement. Single source = hypothesis + `(not confirmed)`.
 Conflicting pairings (≥2 yes vs ≥2 no) = hypothesis (OQ1 → v2 resolution).
+
+## Read path
+
+`bin/brain/get.go`, `stats.go`, and `eval.go` call `internal/brain` with cgo
+(`system_ladybug`). They do not exec Python. Control questions for recall@5
+live in `internal/brain/rank` so CI can test the table without libladybug.
+Python `bin/kb/{get,stats,eval}` remain for GitHub Actions until the runner
+has ladybug cgo. Index/write is still `bin/kb/index`.
+
+## Agent API (D20)
+
+`bin/brain/serve.go` exposes the same `internal/httpapi.Ops` table as OpenAPI
+(`GET /openapi.json`) and MCP (`POST /mcp` JSON-RPC `tools/list` +
+`tools/call`). Tool names match paths: `search`, `get`, `stats`, `audit`.
+Agents should use these endpoints instead of shebang CLIs.

internal/brain/http.go

@@ -7,6 +7,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+
+	"github.com/eSlider/2dph/internal/brain/rank"
 )
 
 // Ready opens the Ladybug file for the life of the serve process.
@@ -17,7 +19,7 @@ func Ready() error {
 // HTTP is the in-process API used by bin/brain/serve.go.
 type HTTP struct{}
 
-func (HTTP) Search(_ context.Context, query string, limit int) ([]byte, error) {
+func (HTTP) Search(ctx context.Context, query string, limit int) ([]byte, error) {
 	hits, err := searchHits(query, "", "", limit)
 	if err != nil {
 		return nil, err
@@ -31,10 +33,13 @@ func (HTTP) Search(_ context.Context, query string, limit int) ([]byte, error) {
 			hits[i].Snippet = string(runes)
 		}
 	}
+	webOut := rank.Deduce(hits, query, "", false, func(q string) rank.SecondSource {
+		return lookupWeb(ctx, q)
+	})
 	var buf bytes.Buffer
 	enc := json.NewEncoder(&buf)
 	enc.SetEscapeHTML(false)
-	if err := enc.Encode(toJSONOut(hits, query, "")); err != nil {
+	if err := enc.Encode(toJSONOut(hits, query, "", webOut)); err != nil {
 		return nil, err
 	}
 	return buf.Bytes(), nil

internal/brain/modelid.go

@@ -0,0 +1,3 @@
+package brain
+
+const ModelID = "minishlab/potion-multilingual-128M"

internal/brain/rank/args.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 )
 
-const Usage = `usage: bin/brain/search.go "query" [--root facts|info] [--repo REPO] [-n N] [--json]
+const Usage = `usage: bin/brain/search.go "query" [--root facts|info] [--repo REPO] [-n N] [--json] [--no-web]
        bin/brain/search.go serve [port]
        bin/brain/search.go --list-model`
 
@@ -17,6 +17,7 @@ type Options struct {
 	Limit     int
 	JSONOut   bool
 	ListModel bool
+	NoWeb     bool
 }
 
 // ParseArgs reads flags. Unknown flags are an error: silently dropping them
@@ -54,6 +55,8 @@ func ParseArgs(args []string) (Options, error) {
 			return opt, fmt.Errorf("--hop is not implemented yet (needs File/FROM_FILE edges)")
 		case "--json":
 			opt.JSONOut = true
+		case "--no-web":
+			opt.NoWeb = true
 		case "--list-model":
 			opt.ListModel = true
 		default:

internal/brain/rank/escalate.go

@@ -0,0 +1,43 @@
+package rank
+
+// SecondSource is the web-search block on a deduction answer.
+// Kept apart from graph hits so "ours" and "not ours" stay visible.
+type SecondSource struct {
+	Status  string            `json:"status"`
+	Note    string            `json:"note,omitempty"`
+	Cached  bool              `json:"cached,omitempty"`
+	Results []SecondSourceHit `json:"results,omitempty"`
+}
+
+type SecondSourceHit struct {
+	Rank    int    `json:"rank"`
+	Title   string `json:"title"`
+	URL     string `json:"url"`
+	Snippet string `json:"snippet"`
+	Engine  string `json:"engine"`
+}
+
+type WebFn func(query string) SecondSource
+
+// ShouldEscalate is true when the default deduction path has no facts hit.
+// `--root facts|info` is a single-root ask: do not mix in the web.
+func ShouldEscalate(hits []Hit, rootFilter string) bool {
+	if rootFilter != "" {
+		return false
+	}
+	for _, h := range hits {
+		if h.Root == "facts" {
+			return false
+		}
+	}
+	return true
+}
+
+// Deduce returns the second-source block, or nil when web must not run.
+func Deduce(hits []Hit, query, rootFilter string, noWeb bool, web WebFn) *SecondSource {
+	if noWeb || web == nil || !ShouldEscalate(hits, rootFilter) {
+		return nil
+	}
+	out := web(query)
+	return &out
+}

internal/brain/rank/escalate_test.go

@@ -0,0 +1,78 @@
+package rank
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestShouldEscalateWhenNoFacts(t *testing.T) {
+	if !ShouldEscalate(nil, "") {
+		t.Fatal("empty local graph must escalate")
+	}
+	if !ShouldEscalate([]Hit{h("i", "info", "docs/a.md")}, "") {
+		t.Fatal("info-only must escalate (not confirmed)")
+	}
+}
+
+func TestShouldNotEscalateWhenFactsConfirm(t *testing.T) {
+	hits := []Hit{h("f", "facts", "docker ps x compose"), h("i", "info", "docs/a.md")}
+	if ShouldEscalate(hits, "") {
+		t.Fatal("facts hit is already confirmed; do not mix web")
+	}
+}
+
+func TestShouldNotEscalateWhenRootFilterSet(t *testing.T) {
+	if ShouldEscalate(nil, "facts") {
+		t.Fatal("--root facts must stay local")
+	}
+	if ShouldEscalate([]Hit{h("i", "info", "x")}, "info") {
+		t.Fatal("--root info must stay local")
+	}
+}
+
+func TestDeduceCallsWebOnlyWhenEscalating(t *testing.T) {
+	called := 0
+	web := func(q string) SecondSource {
+		called++
+		if q != "LadybugDB" {
+			t.Fatalf("query = %q", q)
+		}
+		return SecondSource{Status: "ok", Results: []SecondSourceHit{{Title: "t", URL: "http://example.com"}}}
+	}
+	got := Deduce([]Hit{h("i", "info", "x")}, "LadybugDB", "", false, web)
+	if called != 1 || got == nil || got.Status != "ok" {
+		t.Fatalf("got %+v called=%d", got, called)
+	}
+}
+
+func TestDeduceNilWhenFactsOrNoWeb(t *testing.T) {
+	web := func(string) SecondSource {
+		t.Fatal("web must not run")
+		return SecondSource{}
+	}
+	if Deduce([]Hit{h("f", "facts", "x")}, "q", "", false, web) != nil {
+		t.Fatal("facts")
+	}
+	if Deduce([]Hit{h("i", "info", "x")}, "q", "", true, web) != nil {
+		t.Fatal("--no-web")
+	}
+	if Deduce(nil, "q", "facts", false, web) != nil {
+		t.Fatal("--root facts")
+	}
+	if Deduce(nil, "q", "", false, nil) != nil {
+		t.Fatal("nil web fn")
+	}
+}
+
+func TestParseNoWeb(t *testing.T) {
+	opt, err := ParseArgs([]string{"query", "--no-web", "--json"})
+	if err != nil || !opt.NoWeb || !opt.JSONOut || opt.Query != "query" {
+		t.Fatalf("got %+v err=%v", opt, err)
+	}
+}
+
+func TestUsageNamesNoWeb(t *testing.T) {
+	if !strings.Contains(Usage, "--no-web") {
+		t.Fatalf("usage must name --no-web, got:\n%s", Usage)
+	}
+}

internal/brain/rank/evalq.go

@@ -0,0 +1,16 @@
+package rank
+
+// Eval control questions (recall@5). Kept here so CI can test the gate
+// table without ladybug cgo. The runner lives in internal/brain (cgo).
+const EvalRecallThreshold = 0.95
+
+type EvalQuestion struct {
+	Query    string
+	Fragment string
+}
+
+var EvalQuestions = []EvalQuestion{
+	{"hybrid search fts and vector", "BM25"},
+	{"eslider devops engineer", "DevOps"},
+	{"ladybugdb graph engine storage", "LadybugDB"},
+}

internal/brain/rank/evalq_test.go

@@ -0,0 +1,17 @@
+package rank
+
+import "testing"
+
+func TestEvalQuestionsAreThreeAndThreshold(t *testing.T) {
+	if EvalRecallThreshold != 0.95 {
+		t.Fatalf("threshold = %v", EvalRecallThreshold)
+	}
+	if len(EvalQuestions) != 3 {
+		t.Fatalf("questions = %d, want 3", len(EvalQuestions))
+	}
+	for _, q := range EvalQuestions {
+		if q.Query == "" || q.Fragment == "" {
+			t.Fatalf("empty control: %+v", q)
+		}
+	}
+}

internal/brain/read.go

@@ -0,0 +1,281 @@
+//go:build cgo && system_ladybug
+
+package brain
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/eSlider/2dph/internal/brain/rank"
+)
+
+func MainGet(args []string) int {
+	id, body, jsonOut := "", false, false
+	for _, a := range args {
+		switch {
+		case a == "--body":
+			body = true
+		case a == "--json":
+			jsonOut = true
+		case a == "-h" || a == "--help":
+			fmt.Fprintln(os.Stderr, `usage: bin/brain/get.go <id> [--body] [--json]`)
+			return 0
+		case strings.HasPrefix(a, "-"):
+			fmt.Fprintf(os.Stderr, "brain/get: unknown flag %s\n", a)
+			return 2
+		default:
+			id = a
+		}
+	}
+	if id == "" {
+		fmt.Fprintln(os.Stderr, "brain/get: id required")
+		return 2
+	}
+	if err := openBrain(); err != nil {
+		fmt.Fprintf(os.Stderr, "open brain: %v\n", err)
+		return 1
+	}
+	defer closeBrain()
+	meta, text, err := lookupLeaf(id)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "brain/get: %v\n", err)
+		return 1
+	}
+	out := Dict{
+		{"id", meta["id"]},
+		{"root", meta["root"]},
+		{"confidence", meta["confidence"]},
+		{"source", meta["source"]},
+		{"type", meta["type"]},
+	}
+	if body {
+		out = append(out, KV{"text", text})
+	} else {
+		out = append(out, KV{"snippet", clip(text, 280)})
+	}
+	if jsonOut {
+		m := map[string]any{}
+		for _, kv := range out {
+			m[kv.K] = kv.V
+		}
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "  ")
+		enc.SetEscapeHTML(false)
+		return b2i(enc.Encode(m))
+	}
+	fmt.Print(toYAML(out, 0))
+	return 0
+}
+
+func MainStats(args []string) int {
+	jsonOut := false
+	for _, a := range args {
+		switch a {
+		case "--json":
+			jsonOut = true
+		case "-h", "--help":
+			fmt.Fprintln(os.Stderr, `usage: bin/brain/stats.go [--json]`)
+			return 0
+		default:
+			if strings.HasPrefix(a, "-") {
+				fmt.Fprintf(os.Stderr, "brain/stats: unknown flag %s\n", a)
+				return 2
+			}
+		}
+	}
+	if err := openBrain(); err != nil {
+		fmt.Fprintf(os.Stderr, "open brain: %v\n", err)
+		return 1
+	}
+	defer closeBrain()
+	s, err := leafStats()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "brain/stats: %v\n", err)
+		return 1
+	}
+	if jsonOut {
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "  ")
+		enc.SetEscapeHTML(false)
+		return b2i(enc.Encode(s))
+	}
+	by := s["by_root"].(map[string]int)
+	keys := make([]string, 0, len(by))
+	for k := range by {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	byRoot := make(Dict, 0, len(keys))
+	for _, k := range keys {
+		byRoot = append(byRoot, KV{k, by[k]})
+	}
+	out := Dict{
+		{"total", s["total"]},
+		{"by_root", byRoot},
+		{"db", s["db"]},
+		{"model", s["model"]},
+	}
+	fmt.Print(toYAML(out, 0))
+	return 0
+}
+
+func MainEval(args []string) int {
+	jsonOut := false
+	for _, a := range args {
+		switch a {
+		case "--json":
+			jsonOut = true
+		case "-h", "--help":
+			fmt.Fprintln(os.Stderr, `usage: bin/brain/eval.go [--json]`)
+			return 0
+		default:
+			if strings.HasPrefix(a, "-") {
+				fmt.Fprintf(os.Stderr, "brain/eval: unknown flag %s\n", a)
+				return 2
+			}
+		}
+	}
+	if err := openBrain(); err != nil {
+		fmt.Fprintf(os.Stderr, "open brain: %v\n", err)
+		return 1
+	}
+	defer closeBrain()
+	recalled := 0
+	details := make([]any, 0, len(rank.EvalQuestions))
+	jsDetails := make([]map[string]any, 0, len(rank.EvalQuestions))
+	for _, q := range rank.EvalQuestions {
+		hits, err := queryFTS(q.Query, 5)
+		ok := false
+		if err == nil {
+			frag := strings.ToLower(q.Fragment)
+			for _, h := range hits {
+				if strings.Contains(strings.ToLower(h.Text), frag) {
+					ok = true
+					break
+				}
+			}
+		}
+		if ok {
+			recalled++
+		}
+		details = append(details, Dict{
+			{"q", q.Query},
+			{"fragment", q.Fragment},
+			{"in_top5", ok},
+		})
+		jsDetails = append(jsDetails, map[string]any{
+			"q": q.Query, "fragment": q.Fragment, "in_top5": ok,
+		})
+	}
+	n := len(rank.EvalQuestions)
+	recall := 0.0
+	if n > 0 {
+		recall = float64(recalled) / float64(n)
+	}
+	passed := recall >= rank.EvalRecallThreshold
+	if jsonOut {
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "  ")
+		enc.SetEscapeHTML(false)
+		_ = enc.Encode(map[string]any{
+			"recall@5": round3(recall),
+			"passed":   passed,
+			"gate":     n,
+			"details":  jsDetails,
+		})
+	} else {
+		out := Dict{
+			{"recall@5", round3(recall)},
+			{"passed", passed},
+			{"gate", n},
+			{"details", details},
+		}
+		fmt.Print(toYAML(out, 0))
+	}
+	if !passed {
+		return 2
+	}
+	return 0
+}
+
+func lookupLeaf(id string) (map[string]string, string, error) {
+	if conn == nil {
+		return nil, "", fmt.Errorf("brain not open")
+	}
+	stmt, err := conn.Prepare(
+		"MATCH (l:Leaf {id:$id}) RETURN l.id, l.text, l.root, l.confidence, l.source, l.type",
+	)
+	if err != nil {
+		return nil, "", err
+	}
+	defer stmt.Close()
+	res, err := conn.Execute(stmt, map[string]any{"id": id})
+	if err != nil {
+		return nil, "", err
+	}
+	if !res.HasNext() {
+		return nil, "", fmt.Errorf("no leaf %s", id)
+	}
+	row, err := res.Next()
+	if err != nil {
+		return nil, "", err
+	}
+	vals, err := row.GetAsSlice()
+	if err != nil || len(vals) < 6 {
+		return nil, "", fmt.Errorf("leaf row")
+	}
+	meta := map[string]string{
+		"id":         fmt.Sprint(vals[0]),
+		"root":       fmt.Sprint(vals[2]),
+		"confidence": fmt.Sprint(vals[3]),
+		"source":     fmt.Sprint(vals[4]),
+		"type":       fmt.Sprint(vals[5]),
+	}
+	return meta, fmt.Sprint(vals[1]), nil
+}
+
+func leafStats() (map[string]any, error) {
+	if conn == nil {
+		return nil, fmt.Errorf("brain not open")
+	}
+	res, err := conn.Query("MATCH (l:Leaf) RETURN l.root, count(*)")
+	if err != nil {
+		return nil, err
+	}
+	byRoot := map[string]int{}
+	total := 0
+	for res.HasNext() {
+		row, err := res.Next()
+		if err != nil {
+			return nil, err
+		}
+		vals, err := row.GetAsSlice()
+		if err != nil || len(vals) < 2 {
+			continue
+		}
+		n := int(asInt(vals[1]))
+		byRoot[fmt.Sprint(vals[0])] = n
+		total += n
+	}
+	return map[string]any{
+		"total":   total,
+		"by_root": byRoot,
+		"db":      dbPath(),
+		"model":   ModelID,
+	}, nil
+}
+
+func clip(s string, n int) string {
+	if utf8.RuneCountInString(s) <= n {
+		return s
+	}
+	return string([]rune(s)[:n])
+}
+
+func round3(f float64) float64 {
+	return float64(int(f*1000+0.5)) / 1000
+}

internal/brain/search.go

@@ -68,18 +68,25 @@ func runSearch(args []string) int {
 		}
 	}
 
+	webOut := rank.Deduce(results, query, root, opt.NoWeb, func(q string) rank.SecondSource {
+		return lookupWeb(context.Background(), q)
+	})
+
 	out := Dict{
 		{"query", query},
 		{"root_filter", root},
 		{"count", len(results)},
 		{"results", resultsToDicts(results)},
 	}
+	if webOut != nil {
+		out = append(out, KV{"web", secondToDict(*webOut)})
+	}
 
 	if jsonOut {
 		enc := json.NewEncoder(os.Stdout)
 		enc.SetIndent("", "  ")
 		enc.SetEscapeHTML(false)
-		return b2i(enc.Encode(toJSONOut(results, query, root)))
+		return b2i(enc.Encode(toJSONOut(results, query, root, webOut)))
 	}
 	fmt.Print(toYAML(out, 0))
 	return 0
@@ -172,6 +179,7 @@ type jsonOut struct {
 	RootFilter string             `json:"root_filter"`
 	Count      int                `json:"count"`
 	Results    []jsonHit          `json:"results"`
+	Web        *rank.SecondSource `json:"web,omitempty"`
 }
 
 type jsonHit struct {
@@ -182,7 +190,7 @@ type jsonHit struct {
 	Snippet string  `json:"snippet,omitempty"`
 }
 
-func toJSONOut(hits []Hit, query, rootFilter string) *jsonOut {
+func toJSONOut(hits []Hit, query, rootFilter string, web *rank.SecondSource) *jsonOut {
 	out := make([]jsonHit, len(hits))
 	for i, h := range hits {
 		out[i] = jsonHit{
@@ -198,6 +206,7 @@ func toJSONOut(hits []Hit, query, rootFilter string) *jsonOut {
 		RootFilter: rootFilter,
 		Count:      len(hits),
 		Results:    out,
+		Web:        web,
 	}
 }
 

internal/brain/web.go

@@ -0,0 +1,56 @@
+package brain
+
+import (
+	"context"
+
+	"github.com/eSlider/2dph/internal/brain/rank"
+	"github.com/eSlider/2dph/internal/websearch"
+)
+
+func lookupWeb(ctx context.Context, query string) rank.SecondSource {
+	o := websearch.Lookup(ctx, query, websearch.LookupOpt{Limit: 5})
+	return toSecond(o)
+}
+
+func toSecond(o websearch.Output) rank.SecondSource {
+	hits := make([]rank.SecondSourceHit, 0, len(o.Results))
+	for _, h := range o.Results {
+		hits = append(hits, rank.SecondSourceHit{
+			Rank:    h.Rank,
+			Title:   h.Title,
+			URL:     h.URL,
+			Snippet: h.Snippet,
+			Engine:  h.Engine,
+		})
+	}
+	return rank.SecondSource{
+		Status:  o.Status,
+		Note:    o.Note,
+		Cached:  o.Cached,
+		Results: hits,
+	}
+}
+
+func secondToDict(w rank.SecondSource) Dict {
+	d := Dict{
+		{"status", w.Status},
+	}
+	if w.Note != "" {
+		d = append(d, KV{"note", w.Note})
+	}
+	if w.Cached {
+		d = append(d, KV{"cached", true})
+	}
+	rows := make([]any, 0, len(w.Results))
+	for _, h := range w.Results {
+		rows = append(rows, Dict{
+			{"rank", h.Rank},
+			{"title", h.Title},
+			{"url", h.URL},
+			{"snippet", h.Snippet},
+			{"engine", h.Engine},
+		})
+	}
+	d = append(d, KV{"results", rows})
+	return d
+}

internal/httpapi/mcp.go

@@ -0,0 +1,185 @@
+package httpapi
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+)
+
+type rpcReq struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      json.RawMessage `json:"id"`
+	Method  string          `json:"method"`
+	Params  json.RawMessage `json:"params"`
+}
+
+type rpcErr struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+func (s *Server) handleOpenAPI(w http.ResponseWriter, _ *http.Request) {
+	writeJSON(w, http.StatusOK, OpenAPI())
+}
+
+func (s *Server) handleMCP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		writeJSON(w, http.StatusMethodNotAllowed, map[string]any{"error": "POST JSON-RPC"})
+		return
+	}
+	raw, err := io.ReadAll(io.LimitReader(r.Body, 1<<20))
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]any{"error": "read body"})
+		return
+	}
+	var req rpcReq
+	if err := json.Unmarshal(raw, &req); err != nil {
+		writeJSON(w, http.StatusOK, rpcResult(nil, nil, &rpcErr{-32700, "parse error"}))
+		return
+	}
+	result, rpcErrv, callErr := s.mcpDispatch(r, req)
+	if callErr != nil {
+		writeJSON(w, http.StatusOK, rpcResult(req.ID, nil, &rpcErr{-32603, callErr.Error()}))
+		return
+	}
+	writeJSON(w, http.StatusOK, rpcResult(req.ID, result, rpcErrv))
+}
+
+func (s *Server) mcpDispatch(r *http.Request, req rpcReq) (any, *rpcErr, error) {
+	switch req.Method {
+	case "initialize":
+		return map[string]any{
+			"protocolVersion": "2024-11-05",
+			"capabilities":    map[string]any{"tools": map[string]any{}},
+			"serverInfo":      map[string]any{"name": "2dph", "version": "1"},
+		}, nil, nil
+	case "notifications/initialized", "notifications/cancelled":
+		return map[string]any{}, nil, nil
+	case "tools/list":
+		return map[string]any{"tools": MCPTools()}, nil, nil
+	case "tools/call":
+		out, err := s.mcpCall(r, req.Params)
+		return out, nil, err
+	case "ping":
+		return map[string]any{}, nil, nil
+	default:
+		return nil, &rpcErr{-32601, "method not found"}, nil
+	}
+}
+
+func (s *Server) mcpCall(r *http.Request, params json.RawMessage) (any, error) {
+	var p struct {
+		Name      string         `json:"name"`
+		Arguments map[string]any `json:"arguments"`
+	}
+	if err := json.Unmarshal(params, &p); err != nil {
+		return nil, fmt.Errorf("params")
+	}
+	if p.Arguments == nil {
+		p.Arguments = map[string]any{}
+	}
+	var (
+		body []byte
+		err  error
+	)
+	switch p.Name {
+	case "search":
+		q := strings.TrimSpace(fmt.Sprint(p.Arguments["q"]))
+		if q == "" || q == "<nil>" {
+			return mcpText(`{"error":"q required"}`, true), nil
+		}
+		limit := 10
+		if raw, ok := p.Arguments["n"]; ok {
+			switch n := raw.(type) {
+			case float64:
+				limit = int(n)
+			case string:
+				if v, e := strconv.Atoi(n); e == nil {
+					limit = v
+				}
+			}
+		}
+		if limit < 1 || limit > 100 {
+			return mcpText(`{"error":"n must be int 1..100"}`, true), nil
+		}
+		if !s.tryAcquire(r) {
+			return nil, fmt.Errorf("cancelled")
+		}
+		defer s.release()
+		body, err = s.api.Search(r.Context(), q, limit)
+	case "get":
+		id := strings.TrimSpace(fmt.Sprint(p.Arguments["id"]))
+		if id == "" || id == "<nil>" {
+			return mcpText(`{"error":"id required"}`, true), nil
+		}
+		full := false
+		switch v := p.Arguments["body"].(type) {
+		case bool:
+			full = v
+		case string:
+			full = v == "1" || v == "true"
+		}
+		if !s.tryAcquire(r) {
+			return nil, fmt.Errorf("cancelled")
+		}
+		defer s.release()
+		body, err = s.api.Get(r.Context(), id, full)
+	case "stats":
+		if !s.tryAcquire(r) {
+			return nil, fmt.Errorf("cancelled")
+		}
+		defer s.release()
+		body, err = s.api.Stats(r.Context())
+	case "audit":
+		if !s.tryAcquire(r) {
+			return nil, fmt.Errorf("cancelled")
+		}
+		defer s.release()
+		body, err = s.api.Audit(r.Context())
+	case "ingest":
+		if !s.tryAcquire(r) {
+			return nil, fmt.Errorf("cancelled")
+		}
+		defer s.release()
+		body, err = s.api.Ingest(r.Context())
+	default:
+		return nil, fmt.Errorf("unknown tool %s", p.Name)
+	}
+	if err != nil {
+		return mcpText(err.Error(), true), nil
+	}
+	return mcpText(string(body), false), nil
+}
+
+func mcpText(text string, isError bool) map[string]any {
+	return map[string]any{
+		"content": []any{map[string]any{"type": "text", "text": text}},
+		"isError": isError,
+	}
+}
+
+type rpcResp struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      json.RawMessage `json:"id"`
+	Result  any             `json:"result,omitempty"`
+	Error   *rpcErr         `json:"error,omitempty"`
+}
+
+func rpcResult(id json.RawMessage, result any, err *rpcErr) rpcResp {
+	out := rpcResp{JSONRPC: "2.0", ID: id}
+	if len(id) == 0 {
+		out.ID = []byte("null")
+	}
+	if err != nil {
+		out.Error = err
+		return out
+	}
+	if result == nil {
+		result = map[string]any{}
+	}
+	out.Result = result
+	return out
+}

internal/httpapi/server.go

@@ -48,18 +48,22 @@ func NewServer(api API, workers int) http.Handler {
 
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	switch r.URL.Path {
-	case "/health":
+	case PathHealth:
 		writeJSON(w, http.StatusOK, map[string]any{"status": "ok"})
-	case "/search":
+	case PathSearch:
 		s.handleSearch(w, r)
-	case "/get":
+	case PathGet:
 		s.handleGet(w, r)
-	case "/stats":
+	case PathStats:
 		s.handleJSON(w, r, s.api.Stats)
-	case "/audit":
+	case PathAudit:
 		s.handleJSON(w, r, s.api.Audit)
-	case "/ingest":
+	case PathIngest:
 		s.handleJSON(w, r, s.api.Ingest)
+	case PathOpenAPI:
+		s.handleOpenAPI(w, r)
+	case PathMCP:
+		s.handleMCP(w, r)
 	default:
 		writeJSON(w, http.StatusNotFound, map[string]any{"error": "not found"})
 	}
@@ -112,6 +116,16 @@ func (s *Server) handleJSON(w http.ResponseWriter, r *http.Request, fn func(cont
 	writeAPI(w, body, err)
 }
 
+func (s *Server) tryAcquire(r *http.Request) bool {
+	return s.acquire(nopWriter{}, r)
+}
+
+type nopWriter struct{}
+
+func (nopWriter) Header() http.Header       { return http.Header{} }
+func (nopWriter) Write([]byte) (int, error) { return 0, nil }
+func (nopWriter) WriteHeader(int)           {}
+
 func (s *Server) acquire(w http.ResponseWriter, r *http.Request) bool {
 	select {
 	case s.semaphore <- struct{}{}:

internal/httpapi/spec.go

@@ -0,0 +1,144 @@
+package httpapi
+
+import "strings"
+
+// Shared HTTP surface: OpenAPI paths and MCP tools are generated from Ops.
+// ServeHTTP must keep the same path strings.
+
+type Param struct {
+	Name, In, Type, Description string
+	Required                    bool
+}
+
+type Op struct {
+	Path, Method, ID, Summary string
+	Params                    []Param
+	MCP                       bool
+}
+
+const (
+	PathHealth  = "/health"
+	PathSearch  = "/search"
+	PathGet     = "/get"
+	PathStats   = "/stats"
+	PathAudit   = "/audit"
+	PathIngest  = "/ingest"
+	PathOpenAPI = "/openapi.json"
+	PathMCP     = "/mcp"
+)
+
+var Ops = []Op{
+	{Path: PathHealth, Method: "get", ID: "health", Summary: "liveness"},
+	{
+		Path: PathSearch, Method: "get", ID: "search", Summary: "deduction search (facts → info → web)",
+		MCP: true,
+		Params: []Param{
+			{Name: "q", In: "query", Type: "string", Description: "search query", Required: true},
+			{Name: "n", In: "query", Type: "integer", Description: "hit limit 1..100 (default 10)"},
+		},
+	},
+	{
+		Path: PathGet, Method: "get", ID: "get", Summary: "read one leaf by id",
+		MCP: true,
+		Params: []Param{
+			{Name: "id", In: "query", Type: "string", Description: "leaf id", Required: true},
+			{Name: "body", In: "query", Type: "boolean", Description: "include full text"},
+		},
+	},
+	{Path: PathStats, Method: "get", ID: "stats", Summary: "index health", MCP: true},
+	{Path: PathAudit, Method: "get", ID: "audit", Summary: "facts confidence histogram", MCP: true},
+	{Path: PathIngest, Method: "get", ID: "ingest", Summary: "rebuild hint (write is v2)", MCP: true},
+	{Path: PathOpenAPI, Method: "get", ID: "openapi", Summary: "OpenAPI 3 document for this server"},
+}
+
+func OpenAPI() map[string]any {
+	paths := map[string]any{}
+	for _, op := range Ops {
+		params := make([]any, 0, len(op.Params))
+		for _, p := range op.Params {
+			params = append(params, map[string]any{
+				"name":        p.Name,
+				"in":          p.In,
+				"required":    p.Required,
+				"description": p.Description,
+				"schema":      map[string]any{"type": p.Type},
+			})
+		}
+		item := map[string]any{
+			"operationId": op.ID,
+			"summary":     op.Summary,
+			"responses": map[string]any{
+				"200": map[string]any{
+					"description": "JSON",
+					"content": map[string]any{
+						"application/json": map[string]any{
+							"schema": map[string]any{"type": "object"},
+						},
+					},
+				},
+			},
+		}
+		if len(params) > 0 {
+			item["parameters"] = params
+		}
+		paths[op.Path] = map[string]any{op.Method: item}
+	}
+	return map[string]any{
+		"openapi": "3.0.3",
+		"info": map[string]any{
+			"title":       "2dph brain",
+			"version":     "1",
+			"description": "Same handlers as bin/brain/serve.go. MCP tools at POST /mcp match these paths.",
+		},
+		"paths": paths,
+	}
+}
+
+type MCPTool struct {
+	Name        string         `json:"name"`
+	Description string         `json:"description"`
+	InputSchema map[string]any `json:"inputSchema"`
+}
+
+func MCPTools() []MCPTool {
+	out := make([]MCPTool, 0, len(Ops))
+	for _, op := range Ops {
+		if !op.MCP {
+			continue
+		}
+		props := map[string]any{}
+		var required []string
+		for _, p := range op.Params {
+			props[p.Name] = map[string]any{"type": p.Type, "description": p.Description}
+			if p.Required {
+				required = append(required, p.Name)
+			}
+		}
+		schema := map[string]any{"type": "object", "properties": props}
+		if len(required) > 0 {
+			schema["required"] = required
+		}
+		out = append(out, MCPTool{
+			Name:        op.ID,
+			Description: op.Summary,
+			InputSchema: schema,
+		})
+	}
+	return out
+}
+
+// SkillMarkdown is the Cursor skill fragment generated from Ops/MCPTools.
+func SkillMarkdown() string {
+	var b strings.Builder
+	b.WriteString("# brain HTTP / MCP tools\n\n")
+	b.WriteString("Generated from `internal/httpapi.Ops`. Do not edit by hand.\n\n")
+	b.WriteString("Serve: `bin/brain/serve.go` (`GET /openapi.json`, `POST /mcp`).\n\n")
+	for _, t := range MCPTools() {
+		b.WriteString("- `")
+		b.WriteString(t.Name)
+		b.WriteString("` — ")
+		b.WriteString(t.Description)
+		b.WriteString("\n")
+	}
+	return b.String()
+}

internal/httpapi/spec_test.go

@@ -0,0 +1,99 @@
+package httpapi
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestOpenAPIIncludesCorePaths(t *testing.T) {
+	doc := OpenAPI()
+	raw, err := json.Marshal(doc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	paths, _ := doc["paths"].(map[string]any)
+	for _, p := range []string{"/search", "/get", "/stats", "/audit"} {
+		if _, ok := paths[p]; !ok {
+			t.Fatalf("openapi missing path %s (%s)", p, raw)
+		}
+	}
+}
+
+func TestMCPToolsMatchOpenAPIPaths(t *testing.T) {
+	paths, _ := OpenAPI()["paths"].(map[string]any)
+	tools := MCPTools()
+	if len(tools) == 0 {
+		t.Fatal("no MCP tools")
+	}
+	names := map[string]bool{}
+	for _, tool := range tools {
+		names[tool.Name] = true
+		path := "/" + tool.Name
+		if _, ok := paths[path]; !ok {
+			t.Fatalf("MCP tool %s has no OpenAPI path %s", tool.Name, path)
+		}
+	}
+	for _, need := range []string{"search", "get", "stats", "audit"} {
+		if !names[need] {
+			t.Fatalf("MCP tools missing %s: %v", need, names)
+		}
+	}
+}
+
+func TestOpenAPIHTTP(t *testing.T) {
+	h := NewServer(&fakeSearcher{}, 1)
+	code, body := get(t, h, "/openapi.json")
+	if code != http.StatusOK {
+		t.Fatalf("code = %d body=%s", code, body)
+	}
+	var doc map[string]any
+	if err := json.Unmarshal(body, &doc); err != nil {
+		t.Fatalf("not json: %v", err)
+	}
+	if doc["openapi"] == nil {
+		t.Fatalf("missing openapi version: %s", body)
+	}
+}
+
+func TestMCPToolsListAndCall(t *testing.T) {
+	h := NewServer(&fakeSearcher{}, 1)
+	code, body := postJSON(t, h, "/mcp", `{"jsonrpc":"2.0","id":1,"method":"tools/list"}`)
+	if code != http.StatusOK {
+		t.Fatalf("list code = %d body=%s", code, body)
+	}
+	if !strings.Contains(string(body), `"search"`) {
+		t.Fatalf("tools/list missing search: %s", body)
+	}
+	code, body = postJSON(t, h, "/mcp", `{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"search","arguments":{"q":"matrix","n":3}}}`)
+	if code != http.StatusOK {
+		t.Fatalf("call code = %d body=%s", code, body)
+	}
+	if !strings.Contains(string(body), "matrix") {
+		t.Fatalf("search call body %s", body)
+	}
+}
+
+func TestSkillMarkdownMatchesCommittedFile(t *testing.T) {
+	want, err := os.ReadFile(filepath.Join("..", "..", "skills", "brain", "tools.md"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := SkillMarkdown()
+	if got != string(want) {
+		t.Fatalf("skills/brain/tools.md stale; regenerate from SkillMarkdown()\n--- got ---\n%s\n--- want ---\n%s", got, want)
+	}
+}
+
+func postJSON(t *testing.T, h http.Handler, path, raw string) (int, []byte) {
+	t.Helper()
+	req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(raw))
+	req.Header.Set("Content-Type", "application/json")
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	return rec.Code, rec.Body.Bytes()
+}

internal/websearch/lookup.go

@@ -0,0 +1,122 @@
+package websearch
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	StatusSkipped = "skipped"
+	StatusRefused = "refused"
+)
+
+type LookupOpt struct {
+	Limit     int
+	Timeout   time.Duration
+	EnvPath   string
+	CachePath string
+	Client    *http.Client
+	Now       func() float64
+	Sleep     func(context.Context, time.Duration) error
+}
+
+func Lookup(ctx context.Context, query string, opt LookupOpt) Output {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if opt.Limit <= 0 {
+		opt.Limit = DefaultLimit
+	}
+	if opt.Timeout <= 0 {
+		opt.Timeout = 25 * time.Second
+	}
+	nowFn := opt.Now
+	if nowFn == nil {
+		nowFn = func() float64 { return float64(time.Now().Unix()) }
+	}
+	sleepFn := opt.Sleep
+	if sleepFn == nil {
+		sleepFn = func(ctx context.Context, d time.Duration) error {
+			t := time.NewTimer(d)
+			defer t.Stop()
+			select {
+			case <-t.C:
+				return nil
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+	}
+
+	if reason := PHIReason(query); reason != "" {
+		return Output{Query: query, Status: StatusRefused, Note: reason}
+	}
+
+	cachePath := opt.CachePath
+	if cachePath == "" {
+		cachePath = os.Getenv("BRAIN_SEARCH_CACHE")
+	}
+	if cachePath == "" {
+		cachePath = os.Getenv("HOME") + "/.cache/brain/web-search.sqlite"
+	}
+	cache, err := OpenCache(cachePath)
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "cache: " + err.Error()}
+	}
+	defer cache.Close()
+
+	key := CacheKey(query, nil)
+	now := nowFn()
+	if cached, err := cache.Get(key, CacheTTL, now); err == nil && cached != nil {
+		out := Project(*cached, opt.Limit, DefaultSnippetChars)
+		out.Cached = true
+		return out
+	}
+
+	envPath := opt.EnvPath
+	if envPath == "" {
+		envPath = os.Getenv("BRAIN_SEARCH_ENV")
+	}
+	if envPath == "" {
+		envPath = os.Getenv("HOME") + "/.config/brain/search.env"
+	}
+	conf, err := LoadConfig(envPath)
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "no BRAIN_SEARCH_URL; second source not consulted"}
+	}
+
+	lock, err := os.OpenFile(cachePath+".lock", os.O_CREATE|os.O_RDWR, 0o600)
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "lock: " + err.Error()}
+	}
+	defer lock.Close()
+	if err := unix.Flock(int(lock.Fd()), unix.LOCK_EX); err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "lock: " + err.Error()}
+	}
+	defer unix.Flock(int(lock.Fd()), unix.LOCK_UN)
+
+	last, err := cache.LastCall()
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "cache: " + err.Error()}
+	}
+	if delay := WaitFor(last, nowFn(), MinInterval); delay > 0 {
+		if err := sleepFn(ctx, time.Duration(delay*float64(time.Second))); err != nil {
+			return Output{Query: query, Status: StatusSkipped, Note: "cancelled"}
+		}
+	}
+	_ = cache.MarkCall(nowFn())
+
+	payload, err := Fetch(opt.Client, conf, query, nil, opt.Timeout)
+	if err != nil {
+		return Output{Query: query, Status: StatusThrottled, Note: fmt.Sprintf("request failed: %v", err)}
+	}
+	if Classify(payload) == StatusOK {
+		_ = cache.Put(key, payload, nowFn())
+	}
+	return Project(payload, opt.Limit, DefaultSnippetChars)
+}

internal/websearch/lookup_test.go

@@ -0,0 +1,97 @@
+package websearch
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestLookupRefusesPIIWithoutFetch(t *testing.T) {
+	hits := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
+		hits++
+	}))
+	defer srv.Close()
+	out := Lookup(context.Background(), "Personalnummer 12", LookupOpt{
+		EnvPath: writeEnv(t, srv.URL),
+		CachePath: filepath.Join(t.TempDir(), "c.sqlite"),
+		Client:    srv.Client(),
+		Sleep:     func(context.Context, time.Duration) error { return nil },
+	})
+	if out.Status != StatusRefused {
+		t.Fatalf("status = %s", out.Status)
+	}
+	if hits != 0 {
+		t.Fatal("PII query left the host")
+	}
+}
+
+func TestLookupSkipsWhenNoConfig(t *testing.T) {
+	out := Lookup(context.Background(), "LadybugDB", LookupOpt{
+		EnvPath:   filepath.Join(t.TempDir(), "missing.env"),
+		CachePath: filepath.Join(t.TempDir(), "c.sqlite"),
+		Sleep:     func(context.Context, time.Duration) error { return nil },
+	})
+	if out.Status != StatusSkipped {
+		t.Fatalf("status = %s", out.Status)
+	}
+}
+
+func TestLookupFetchesOnceAndCaches(t *testing.T) {
+	hits := 0
+	payload := Payload{Query: "x", Results: []RawHit{{Title: "t", URL: "http://example.com", Content: "c", Engine: "bing"}}}
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		hits++
+		json.NewEncoder(w).Encode(payload)
+	}))
+	defer srv.Close()
+	opt := LookupOpt{
+		EnvPath:   writeEnv(t, srv.URL),
+		CachePath: filepath.Join(t.TempDir(), "c.sqlite"),
+		Client:    srv.Client(),
+		Now:       func() float64 { return 1_000 },
+		Sleep:     func(context.Context, time.Duration) error { return nil },
+	}
+	a := Lookup(context.Background(), "LadybugDB", opt)
+	b := Lookup(context.Background(), "LadybugDB", opt)
+	if a.Status != StatusOK || b.Status != StatusOK {
+		t.Fatalf("a=%s b=%s", a.Status, b.Status)
+	}
+	if hits != 1 {
+		t.Fatalf("hits = %d, want 1 (second from cache)", hits)
+	}
+	if !b.Cached {
+		t.Fatal("second lookup not cached")
+	}
+}
+
+func TestLookupEmptyIsThrottled(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(`{"query":"x","results":[]}`))
+	}))
+	defer srv.Close()
+	out := Lookup(context.Background(), "LadybugDB", LookupOpt{
+		EnvPath:   writeEnv(t, srv.URL),
+		CachePath: filepath.Join(t.TempDir(), "c.sqlite"),
+		Client:    srv.Client(),
+		Now:       func() float64 { return 1_000 },
+		Sleep:     func(context.Context, time.Duration) error { return nil },
+	})
+	if out.Status != StatusThrottled {
+		t.Fatalf("status = %s", out.Status)
+	}
+}
+
+func writeEnv(t *testing.T, url string) string {
+	t.Helper()
+	p := filepath.Join(t.TempDir(), "search.env")
+	if err := os.WriteFile(p, []byte("BRAIN_SEARCH_URL="+url+"\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	return p
+}

skills/brain/SKILL.md

@@ -28,7 +28,7 @@ bin/brain/search.go "onlyoffice postgres" --root facts # restrict to confirmed
 bin/brain/search.go "where is cs-lexicon" --json | yq '.[].ref'
 bin/brain/get.go <id> --body                           # full chunk only when needed
 bin/brain/stats.go                                     # index health
-bin/brain/eval.go                                      # recall@5 >= 0.95 gate
+bin/brain/eval.go                                      # recall@5 >= 0.95 gate (Go; Python bin/kb/eval is CI fallback)
 ```
 
 `bin/kb/search` is a deprecated wrapper. `--hop` errors (File/FROM_FILE edges
@@ -39,8 +39,12 @@ are not wired yet); do not treat it as a graph walk.
 - Search before you read. Never grep a repo for a concept the graph covers.
 - `--root facts` returns only confirmed evidence-linked answers. Default shows
   facts first, then info leafs clearly marked `(not confirmed)`.
+- If there is no facts hit, `bin/brain/search.go` consults SearXNG and adds a
+  `web` block (kept apart from graph hits). `throttled` / `skipped` / `refused`
+  are not evidence of absence. `--root facts|info` and `--no-web` skip the web.
 - If recall looks wrong, run `bin/brain/eval.go`; it gates control questions and
   should stay at or above 95% recall@5.
-- Escalate to `web-search` (the `web-search` skill) as the independent second
+- Agents: `GET /openapi.json` and `POST /mcp` on `bin/brain/serve.go` (same
-  source when both local roots cannot confirm; never report an unconfirmed
+  handlers; tool names match paths `search`/`get`/`stats`/`audit`). Generated
-  single-source local answer as fact.
+  list: [tools.md](tools.md).
+- Never report an unconfirmed single-source local answer as fact.

skills/brain/tools.md

@@ -0,0 +1,11 @@
+# brain HTTP / MCP tools
+
+Generated from `internal/httpapi.Ops`. Do not edit by hand.
+
+Serve: `bin/brain/serve.go` (`GET /openapi.json`, `POST /mcp`).
+
+- `search` — deduction search (facts → info → web)
+- `get` — read one leaf by id
+- `stats` — index health
+- `audit` — facts confidence histogram
+- `ingest` — rebuild hint (write is v2)

skills/db-yaml/SKILL.md

@@ -1,39 +0,0 @@
----
-name: db-yaml
-description: >-
-  Read any Postgres as compact YAML through db/psql-yq, with a read-only guard and
-  named profiles. Use when a task needs table contents, column types or a SELECT
-  against cs_brain or another project database.
----
-
-# db-yaml
-
-`bin/db/psql-yq` (vendored in this repo) talks to Postgres and returns YAML,
-which is far cheaper than a psql ASCII table and easy to slice with `yq`.
-
-```bash
-bin/db/psql-yq --profile onlyoffice -s document_asset   # column list
-bin/db/psql-yq --profile onlyoffice -t task_result -l 20  # sample rows as YAML
-bin/db/psql-yq --profile onlyoffice -c 'SELECT ...'     # query -> YAML
-```
-
-Ad-hoc targets without a profile:
-
-```bash
-bin/db/psql-yq --container my-pg --db app -c 'SELECT 1'
-bin/db/psql-yq --dsn 'postgres://user@host:5432/db' -c 'SELECT 1'
-```
-
-## Profiles
-
-Connection details live in `~/.config/brain/db-profiles.yml` (mode 600), never in a
-project repo. A profile names either a `container` or a `host`; passwords are read
-from a separate `password_env_file` and never appear in argv.
-
-## Rules
-
-- **Read-only.** Any `insert|update|delete|drop|truncate|alter|create|grant|
-  revoke|vacuum|copy` is rejected with exit 3. Do not work around it.
-- **PII.** `cs_brain` holds client data. Aggregate and count freely; never copy
-  names or addresses into chat, issues or docs.
-- Use `-l` to keep samples small. Twenty rows answer most questions.

skills/postgres/SKILL.md

@@ -0,0 +1,39 @@
+---
+name: postgres
+description: >-
+  Read Postgres as compact YAML through bin/postgres/query.go (read-only
+  guard, named profiles). Use when a task needs table contents, column types,
+  or a SELECT against an ops database.
+---
+
+# postgres
+
+`bin/postgres/query.go` wraps vendored `bin/db/psql-yq`. Output is YAML
+(cheaper than psql ASCII, easy to slice with `yq`).
+
+```bash
+bin/postgres/query.go --profile onlyoffice -s document_asset   # column list
+bin/postgres/query.go --profile onlyoffice -t task_result -l 20  # sample rows
+bin/postgres/query.go --profile onlyoffice -c 'SELECT ...'     # query → YAML
+```
+
+Ad-hoc targets without a profile:
+
+```bash
+bin/postgres/query.go --container my-pg --db app -c 'SELECT 1'
+bin/postgres/query.go --dsn 'postgres://user@host:5432/db' -c 'SELECT 1'
+```
+
+## Profiles
+
+Connection details live in `$HOME/.config/brain/db-profiles.yml` (mode 600),
+never in a project repo. A profile names either a `container` or a `host`;
+passwords are read from a separate `password_env_file` and never appear in argv.
+
+## Rules
+
+- **Read-only.** Any `insert|update|delete|drop|truncate|alter|create|grant|
+  revoke|vacuum|copy` is rejected with exit 3. Do not work around it.
+- **PII.** Client CRM databases: aggregate and count freely; never copy names
+  or addresses into chat, issues or docs.
+- Use `-l` to keep samples small. Twenty rows answer most questions.