diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 50d2625..41f9f99 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,6 +19,10 @@ jobs:
         with:
           fetch-depth: 0
 
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
       - name: Install uv
         uses: astral-sh/setup-uv@v6
         with:
@@ -32,23 +36,19 @@ jobs:
           bash -n bin/db/psql-yq
           bash -n bin/db/ssh-tunnel
           bash -n bin/docker-entrypoint
+          bash -n bin/kb/search
 
       - name: Python unit tests (offline, vendored tools)
         run: |
           uv run python -m unittest discover -s bin/tools -t .
 
-      - name: Go tests (server + watch packages)
+      - name: Go tests (root module, no ladybug cgo)
         run: |
           go vet ./...
           go test ./... -count=1
 
-      - name: kbsearch ranking tests (no cgo / no ladybug)
-        working-directory: bin/kbsearch
-        run: go test ./rank -count=1
-
-      - name: Go tests (chats nested module)
-        working-directory: bin/chats
-        run: go test ./... -count=1
+      - name: brain ranking tests (no cgo / no ladybug)
+        run: go test ./internal/brain/rank -count=1
 
       - name: facts/audit self (lexicon consistency, no network)
         run: |
diff --git a/.gitignore b/.gitignore
index defce95..e3cb108 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@ __pycache__/
 .env
 .secrets/
 lib-ladybug/
+go.work.local
diff --git a/AGENTS.md b/AGENTS.md
index c1307fe..3ab90d6 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -35,7 +35,9 @@ Read first: [PLAN](PLAN.md) → [docs](docs/).
 PLAN.md       decisions + execution + open questions
 docs/         published docs
 skills/       in-project agent skills (vendored, no external links)
-bin/          self-describing tools bin/{subject}/{method} (shebang)
+bin/          self-describing tools bin/{subject}/{method}.go (shebang)
+bin/brain/    search.go (deduction); libs in internal/brain
+internal/     shared Go (brain/rank is cgo-free)
 bin/serve.go  async Go HTTP server entry (self-executing go run shebang)
 bin/watch/    corpus watcher Go package (mtimes, no inotify deps)
 bin/server/   async Go HTTP server (goroutines, bounded worker pool)
@@ -74,7 +76,8 @@ bin/mail/index_mail                                                     # rebuil
 ```bash
 bin/facts/audit ["self"|"facts"|"info"|"stale"]   # 2-source + staleness gate
 bin/facts/crm [--dry-run]                         # proof person↔company/company↔project (ooCRM × corpus SoT)
-bin/kb/search "query" [--hop N] [--repo X]        # deduction search → YAML
+bin/kb/search "query" [--repo X]                  # deprecated wrapper → bin/brain/search.go
+bin/brain/search.go "query" [--root facts|info]   # deduction search → YAML
 bin/md/tables                                     # what the graph holds → YAML
 bin/brain/deduce "question"                       # thinking wrapper
 ```
diff --git a/PLAN.md b/PLAN.md
index 5230b91..5f66157 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -37,7 +37,7 @@ detective method: **a fact needs ≥2 independent sources or it is
 | D11 | strong/weak | `root` column: `facts` (strong) vs `info` (weak). Answer is `confirmed` only from facts root. |
 | D12 | transactional | facts and info split by root but **written in the same Ladybug transaction (ACID)** on every write. |
 | D13 | portfolio | start graph `(Person:eslider)-[:HAS]->(Portfolio)`, associate other natural/juristic persons later. |
-| D14 | tooling style | `bin/{subject}/{method}` self-describing: shebang line 1, usage comment from line 2. Go shebang: `///usr/bin/env go run "$0" "$@"; exit`. |
+| 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. |
 
diff --git a/bin/brain/doc.go b/bin/brain/doc.go
new file mode 100644
index 0000000..a132c92
--- /dev/null
+++ b/bin/brain/doc.go
@@ -0,0 +1,3 @@
+// Commands in this directory are shebang mains (search.go).
+// search.go is behind the system_ladybug build tag (cgo).
+package main
diff --git a/bin/brain/search.go b/bin/brain/search.go
new file mode 100755
index 0000000..78ce932
--- /dev/null
+++ b/bin/brain/search.go
@@ -0,0 +1,23 @@
+//usr/bin/env go run -tags=system_ladybug "$0" "$@"; exit
+//go:build cgo && system_ladybug
+//
+// 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 serve [port]
+//	./bin/brain/search.go --list-model
+//
+// Needs CGO + libladybug (CGO_CFLAGS/CGO_LDFLAGS). Prefer the wrapper
+// bin/kb/search which sets those and builds a binary for the embed daemon.
+// NOTE: never run `gofmt -w` on this file — it breaks the shebang.
+package main
+
+import (
+	"os"
+
+	"github.com/eSlider/2dph/internal/brain"
+)
+
+func main() {
+	os.Exit(brain.Main(os.Args[1:]))
+}
diff --git a/bin/chats/go.mod b/bin/chats/go.mod
deleted file mode 100644
index 9df1766..0000000
--- a/bin/chats/go.mod
+++ /dev/null
@@ -1,3 +0,0 @@
-module github.com/eSlider/2dph/bin/chats
-
-go 1.25.0
diff --git a/bin/kb/search b/bin/kb/search
index 3c24a47..5b4af3d 100755
--- a/bin/kb/search
+++ b/bin/kb/search
@@ -1,34 +1,37 @@
 #!/usr/bin/env bash
-# bin/kb/search - Go deduction search over the brain (model served by daemon).
-# Builds the kbsearch binary on first run / when source changes, then execs it.
+# bin/kb/search — deprecated wrapper. Use bin/brain/search.go.
+# Sets CGO for ladybug, builds a binary (embed daemon needs a real executable),
+# then execs it. Prints one deprecation line.
 set -euo pipefail
 
-KB="$(cd "$(dirname "$0")/../.." && pwd)"
-BIN="$KB/var/bin/kbsearch"
-SRC="$KB/bin/kbsearch"
+ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+BIN="$ROOT/var/bin/brain-search"
+SRC="$ROOT/internal/brain"
+CMD="$ROOT/bin/brain"
 
-mkdir -p "$KB/var/bin"
+mkdir -p "$ROOT/var/bin"
 
-# Rebuild if binary missing or any .go source newer
 need_build=0
 if [ ! -x "$BIN" ]; then
-    need_build=1
+	need_build=1
 else
-    # Check if any .go in kbsearch is newer than binary
-    while IFS= read -r -d '' f; do
-        if [ "$f" -nt "$BIN" ]; then
-            need_build=1
-            break
-        fi
-    done < <(find "$SRC" -name '*.go' -print0 2>/dev/null)
+	while IFS= read -r -d '' f; do
+		if [ "$f" -nt "$BIN" ]; then
+			need_build=1
+			break
+		fi
+	done < <(find "$SRC" "$CMD" -name '*.go' -print0 2>/dev/null)
 fi
 
 if [ "$need_build" -eq 1 ]; then
-    echo "Building kbsearch..." >&2
-    (cd "$SRC" && \
-        CGO_CFLAGS="-I$KB/lib-ladybug" \
-        CGO_LDFLAGS="-L$KB/lib-ladybug -Wl,-rpath,$KB/lib-ladybug" \
-        go build -tags system_ladybug -o "$BIN" .) || exit 1
+	echo "Building brain/search..." >&2
+	(
+		cd "$ROOT" &&
+			CGO_CFLAGS="-I$ROOT/lib-ladybug" \
+			CGO_LDFLAGS="-L$ROOT/lib-ladybug -Wl,-rpath,$ROOT/lib-ladybug" \
+			go build -tags system_ladybug -o "$BIN" ./bin/brain
+	) || exit 1
 fi
 
-exec "$BIN" "$@"
\ No newline at end of file
+echo "bin/kb/search is deprecated; use bin/brain/search.go" >&2
+exec "$BIN" "$@"
diff --git a/bin/kbsearch/go.mod b/bin/kbsearch/go.mod
deleted file mode 100644
index 5054e8e..0000000
--- a/bin/kbsearch/go.mod
+++ /dev/null
@@ -1,23 +0,0 @@
-module github.com/eSlider/2dph/bin/kbsearch
-
-go 1.26.0
-
-require (
-	github.com/LadybugDB/go-ladybug v0.17.0
-	github.com/chewxy/math32 v1.11.2
-	github.com/daulet/tokenizers v1.27.0
-)
-
-require (
-	github.com/apache/arrow-go/v18 v18.6.0 // indirect
-	github.com/goccy/go-json v0.10.6 // indirect
-	github.com/google/flatbuffers v25.12.19+incompatible // indirect
-	github.com/google/uuid v1.6.0 // indirect
-	github.com/klauspost/compress v1.18.5 // indirect
-	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
-	github.com/pierrec/lz4/v4 v4.1.26 // indirect
-	github.com/shopspring/decimal v1.4.0 // indirect
-	github.com/zeebo/xxh3 v1.1.0 // indirect
-	golang.org/x/exp v0.0.0-20260112195511-716be5621a96 // indirect
-	golang.org/x/sys v0.43.0 // indirect
-)
diff --git a/bin/kbsearch/go.sum b/bin/kbsearch/go.sum
deleted file mode 100644
index 0064c1b..0000000
--- a/bin/kbsearch/go.sum
+++ /dev/null
@@ -1,44 +0,0 @@
-github.com/LadybugDB/go-ladybug v0.17.0 h1:RXDbkBjrbRmLdEbhGl4CLOIEzSt09gbP0n9UbKDEfwI=
-github.com/LadybugDB/go-ladybug v0.17.0/go.mod h1:GeIXmE8XyF5TFS94NAuTag7vgCC+no/HTBMRA6Rd5Cs=
-github.com/andybalholm/brotli v1.2.1 h1:R+f5xP285VArJDRgowrfb9DqL18yVK0gKAW/F+eTWro=
-github.com/andybalholm/brotli v1.2.1/go.mod h1:rzTDkvFWvIrjDXZHkuS16NPggd91W3kUSvPlQ1pLaKY=
-github.com/apache/arrow-go/v18 v18.6.0 h1:GX/Jyd3R7mCLiECAwY9FWbbaYblie2WXBSz4Sw8fNpM=
-github.com/apache/arrow-go/v18 v18.6.0/go.mod h1:gm3MiPpY82fLYK5VKPB3WoJbsiLVDfT7flD5/vHReKw=
-github.com/apache/thrift v0.22.0 h1:r7mTJdj51TMDe6RtcmNdQxgn9XcyfGDOzegMDRg47uc=
-github.com/apache/thrift v0.22.0/go.mod h1:1e7J/O1Ae6ZQMTYdy9xa3w9k+XHWPfRvdPyJeynQ+/g=
-github.com/chewxy/math32 v1.11.2 h1:IufN08Zwr1NKuWfY+4Tz55BcwKmyKKNdOP7KtumehnM=
-github.com/chewxy/math32 v1.11.2/go.mod h1:dOB2rcuFrCn6UHrze36WSLVPKtzPMRAQvBvUwkSsLqs=
-github.com/daulet/tokenizers v1.27.0 h1:MmFYAEDFz69s/nNQfHg59DWqHz3v94m99kEZ/JbL+s4=
-github.com/daulet/tokenizers v1.27.0/go.mod h1:YjFY1o1HGMyWkQgbXJDghhvke/yFDp2vGdIO2hYs4MQ=
-github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
-github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/goccy/go-json v0.10.6 h1:p8HrPJzOakx/mn/bQtjgNjdTcN+/S6FcG2CTtQOrHVU=
-github.com/goccy/go-json v0.10.6/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
-github.com/google/flatbuffers v25.12.19+incompatible h1:haMV2JRRJCe1998HeW/p0X9UaMTK6SDo0ffLn2+DbLs=
-github.com/google/flatbuffers v25.12.19+incompatible/go.mod h1:1AeVuKshWv4vARoZatz6mlQ0JxURH0Kv5+zNeJKJCa8=
-github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
-github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/klauspost/compress v1.18.5 h1:/h1gH5Ce+VWNLSWqPzOVn6XBO+vJbCNGvjoaGBFW2IE=
-github.com/klauspost/compress v1.18.5/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
-github.com/klauspost/cpuid/v2 v2.3.0 h1:S4CRMLnYUhGeDFDqkGriYKdfoFlDnMtqTiI/sFzhA9Y=
-github.com/klauspost/cpuid/v2 v2.3.0/go.mod h1:hqwkgyIinND0mEev00jJYCxPNVRVXFQeu1XKlok6oO0=
-github.com/pierrec/lz4/v4 v4.1.26 h1:GrpZw1gZttORinvzBdXPUXATeqlJjqUG/D87TKMnhjY=
-github.com/pierrec/lz4/v4 v4.1.26/go.mod h1:EoQMVJgeeEOMsCqCzqFm2O0cJvljX2nGZjcRIPL34O4=
-github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
-github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/shopspring/decimal v1.4.0 h1:bxl37RwXBklmTi0C79JfXCEBD1cqqHt0bbgBAGFp81k=
-github.com/shopspring/decimal v1.4.0/go.mod h1:gawqmDU56v4yIKSwfBSFip1HdCCXN8/+DMd9qYNcwME=
-github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
-github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
-github.com/zeebo/assert v1.3.0 h1:g7C04CbJuIDKNPFHmsk4hwZDO5O+kntRxzaUoNXj+IQ=
-github.com/zeebo/assert v1.3.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
-github.com/zeebo/xxh3 v1.1.0 h1:s7DLGDK45Dyfg7++yxI0khrfwq9661w9EN78eP/UZVs=
-github.com/zeebo/xxh3 v1.1.0/go.mod h1:IisAie1LELR4xhVinxWS5+zf1lA4p0MW4T+w+W07F5s=
-golang.org/x/exp v0.0.0-20260112195511-716be5621a96 h1:Z/6YuSHTLOHfNFdb8zVZomZr7cqNgTJvA8+Qz75D8gU=
-golang.org/x/exp v0.0.0-20260112195511-716be5621a96/go.mod h1:nzimsREAkjBCIEFtHiYkrJyT+2uy9YZJB7H1k68CXZU=
-golang.org/x/sys v0.43.0 h1:Rlag2XtaFTxp19wS8MXlJwTvoh8ArU6ezoyFsMyCTNI=
-golang.org/x/sys v0.43.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
-gonum.org/v1/gonum v0.17.0 h1:VbpOemQlsSMrYmn7T2OUvQ4dqxQXU+ouZFQsZOx50z4=
-gonum.org/v1/gonum v0.17.0/go.mod h1:El3tOrEuMpv2UdMrbNlKEh9vd86bmQ6vqIcDwxEOc1E=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/bin/kbsearch/main.go b/bin/kbsearch/main.go
deleted file mode 100644
index b5ac729..0000000
--- a/bin/kbsearch/main.go
+++ /dev/null
@@ -1,46 +0,0 @@
-// bin/kbsearch - the Go implementation of bin/kb/search (nested module so the
-// root `go test ./...` and CI never compile it against native ladyships).
-//
-// Usage (built/run by ./bin/kb/search):
-//
-//	kbsearch "query" [--root facts|info] [--repo P] [-n N] [--json]
-//	kbsearch serve [port]           start the embedding daemon
-//	kbsearch --list-model           print the resolved model dir
-//
-// The potion-multilingual model is loaded only in `serve`; a CLI reuses the
-// daemon over localhost HTTP (KBSEARCH_PORT, default 17830) and starts one in
-// the background when none answers. KBSEARCH_NO_DAEMON=1 skips that and embeds
-// in-process instead.
-package main
-
-import (
-	"fmt"
-	"log"
-	"os"
-	"strconv"
-)
-
-func main() {
-	if len(os.Args) > 1 && os.Args[1] == "serve" {
-		port := 17830
-		if len(os.Args) > 2 {
-			if p, err := strconv.Atoi(os.Args[2]); err == nil {
-				port = p
-			}
-		}
-		if err := serve(port); err != nil {
-			log.Fatalf("kbsearch serve: %v", err)
-		}
-		return
-	}
-	if len(os.Args) > 1 && os.Args[1] == "--list-model" {
-		dir, err := modelDir()
-		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
-		}
-		fmt.Println(dir)
-		return
-	}
-	os.Exit(runSearch(os.Args[1:]))
-}
diff --git a/bin/tools/test_bin_layout.py b/bin/tools/test_bin_layout.py
new file mode 100644
index 0000000..bf7e9e7
--- /dev/null
+++ b/bin/tools/test_bin_layout.py
@@ -0,0 +1,36 @@
+"""D14 layout: bin/{subject}/{method}.go, libs in internal/, one go.mod."""
+from __future__ import annotations
+
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+
+
+class BinLayoutTest(unittest.TestCase):
+    def test_brain_search_shebang_exists(self) -> None:
+        p = ROOT / "bin" / "brain" / "search.go"
+        self.assertTrue(p.is_file(), "missing bin/brain/search.go")
+        first = p.read_text().splitlines()[0]
+        self.assertTrue(
+            first.startswith("//usr/bin/env go run"),
+            f"shebang first line, got {first!r}",
+        )
+
+    def test_no_nested_go_mod_under_bin(self) -> None:
+        nested = list((ROOT / "bin").rglob("go.mod"))
+        self.assertEqual(nested, [], f"nested go.mod files: {nested}")
+
+    def test_rank_lives_in_internal_brain(self) -> None:
+        self.assertTrue(
+            (ROOT / "internal" / "brain" / "rank" / "rank.go").is_file(),
+            "ranking must live in internal/brain/rank (cgo-free)",
+        )
+        self.assertFalse(
+            (ROOT / "bin" / "kbsearch").exists(),
+            "bin/kbsearch nested module must be gone",
+        )
+
+    def test_no_main_go_under_bin_brain(self) -> None:
+        main = ROOT / "bin" / "brain" / "main.go"
+        self.assertFalse(main.exists(), "bin/brain/main.go is not a method")
diff --git a/go.mod b/go.mod
index 2d704f6..79ccecf 100644
--- a/go.mod
+++ b/go.mod
@@ -1,8 +1,25 @@
 module github.com/eSlider/2dph
 
-go 1.25.0
+go 1.26
 
 require (
+	github.com/LadybugDB/go-ladybug v0.17.0
 	github.com/arran4/golang-ical v0.3.5
+	github.com/chewxy/math32 v1.11.2
+	github.com/daulet/tokenizers v1.27.0
 	golang.org/x/text v0.40.0
 )
+
+require (
+	github.com/apache/arrow-go/v18 v18.6.0 // indirect
+	github.com/goccy/go-json v0.10.6 // indirect
+	github.com/google/flatbuffers v25.12.19+incompatible // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/klauspost/compress v1.18.5 // indirect
+	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
+	github.com/pierrec/lz4/v4 v4.1.26 // indirect
+	github.com/shopspring/decimal v1.4.0 // indirect
+	github.com/zeebo/xxh3 v1.1.0 // indirect
+	golang.org/x/exp v0.0.0-20260112195511-716be5621a96 // indirect
+	golang.org/x/sys v0.43.0 // indirect
+)
diff --git a/go.sum b/go.sum
index 5962f4f..e7bf4ab 100644
--- a/go.sum
+++ b/go.sum
@@ -1,14 +1,50 @@
+github.com/LadybugDB/go-ladybug v0.17.0 h1:RXDbkBjrbRmLdEbhGl4CLOIEzSt09gbP0n9UbKDEfwI=
+github.com/LadybugDB/go-ladybug v0.17.0/go.mod h1:GeIXmE8XyF5TFS94NAuTag7vgCC+no/HTBMRA6Rd5Cs=
+github.com/andybalholm/brotli v1.2.1 h1:R+f5xP285VArJDRgowrfb9DqL18yVK0gKAW/F+eTWro=
+github.com/andybalholm/brotli v1.2.1/go.mod h1:rzTDkvFWvIrjDXZHkuS16NPggd91W3kUSvPlQ1pLaKY=
+github.com/apache/arrow-go/v18 v18.6.0 h1:GX/Jyd3R7mCLiECAwY9FWbbaYblie2WXBSz4Sw8fNpM=
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 github.com/arran4/golang-ical v0.3.5 h1:bbz6ld4dC+MmCKiFfOd6SkmIGnhNMBACZ485ULh7p9A=
 github.com/arran4/golang-ical v0.3.5/go.mod h1:OnguFgjN0Hmx8jzpmWcC+AkHio94ujmLHKoaef7xQh8=
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diff --git a/go.work b/go.work
new file mode 100644
index 0000000..f746806
--- /dev/null
+++ b/go.work
@@ -0,0 +1,3 @@
+go 1.26
+
+use .
diff --git a/bin/kbsearch/brain.go b/internal/brain/db.go
similarity index 96%
rename from bin/kbsearch/brain.go
rename to internal/brain/db.go
index caf3644..cce5e9b 100644
--- a/bin/kbsearch/brain.go
+++ b/internal/brain/db.go
@@ -1,5 +1,6 @@
-// Brain connection management using go-ladybug.
-package main
+//go:build cgo && system_ladybug
+
+package brain
 
 import (
 	"fmt"
diff --git a/internal/brain/doc.go b/internal/brain/doc.go
new file mode 100644
index 0000000..d5670bd
--- /dev/null
+++ b/internal/brain/doc.go
@@ -0,0 +1,3 @@
+// Package brain is deduction search over Ladybug (FTS + HNSW).
+// Query/embed code that needs cgo lives behind the system_ladybug tag.
+package brain
diff --git a/bin/kbsearch/model.go b/internal/brain/model.go
similarity index 99%
rename from bin/kbsearch/model.go
rename to internal/brain/model.go
index c8735fa..c16cba4 100644
--- a/bin/kbsearch/model.go
+++ b/internal/brain/model.go
@@ -1,9 +1,11 @@
+//go:build cgo && system_ladybug
+
 // StaticModel wraps the potion-multilingual-128m embedding model.
 //
 // Mirrors model2vec.StaticModel: tokenizer (daulet Unigram) + safetensors matrix.
 // Embed(text) applies the same preprocessing: median_token_length pre-truncation,
 // add_special_tokens=false, drop unk (id=1), truncate to 512, mean pool, L2 normalize +1e-32.
-package main
+package brain
 
 import (
 	"encoding/json"
diff --git a/bin/kbsearch/modeldir.go b/internal/brain/modeldir.go
similarity index 94%
rename from bin/kbsearch/modeldir.go
rename to internal/brain/modeldir.go
index 7913745..a075aae 100644
--- a/bin/kbsearch/modeldir.go
+++ b/internal/brain/modeldir.go
@@ -1,5 +1,4 @@
-// modelDir returns the resolved potion-multilingual-128m model directory.
-package main
+package brain
 
 import (
 	"fmt"
diff --git a/bin/kbsearch/rank/args.go b/internal/brain/rank/args.go
similarity index 90%
rename from bin/kbsearch/rank/args.go
rename to internal/brain/rank/args.go
index 72263e6..dd4970f 100644
--- a/bin/kbsearch/rank/args.go
+++ b/internal/brain/rank/args.go
@@ -6,9 +6,9 @@ import (
 	"strings"
 )
 
-const Usage = `usage: kbsearch "query" [--root facts|info] [--repo REPO] [-n N] [--json]
-       kbsearch serve [port]
-       kbsearch --list-model`
+const Usage = `usage: bin/brain/search.go "query" [--root facts|info] [--repo REPO] [-n N] [--json]
+       bin/brain/search.go serve [port]
+       bin/brain/search.go --list-model`
 
 type Options struct {
 	Query     string
diff --git a/bin/kbsearch/rank/query.go b/internal/brain/rank/query.go
similarity index 100%
rename from bin/kbsearch/rank/query.go
rename to internal/brain/rank/query.go
diff --git a/bin/kbsearch/rank/rank.go b/internal/brain/rank/rank.go
similarity index 96%
rename from bin/kbsearch/rank/rank.go
rename to internal/brain/rank/rank.go
index 474836b..4cdf47b 100644
--- a/bin/kbsearch/rank/rank.go
+++ b/internal/brain/rank/rank.go
@@ -1,4 +1,4 @@
-// Package rank is the cgo-free ranking and CLI parsing for kbsearch.
+// Package rank is the cgo-free ranking and CLI parsing for brain search.
 // CI can `go test ./rank` without the native ladybug library.
 package rank
 
diff --git a/bin/kbsearch/rank/rank_test.go b/internal/brain/rank/rank_test.go
similarity index 95%
rename from bin/kbsearch/rank/rank_test.go
rename to internal/brain/rank/rank_test.go
index 838acfc..15e0eb1 100644
--- a/bin/kbsearch/rank/rank_test.go
+++ b/internal/brain/rank/rank_test.go
@@ -136,6 +136,12 @@ func TestListModelNeedsNoQuery(t *testing.T) {
 	}
 }
 
+func TestUsageNamesBrainSearch(t *testing.T) {
+	if !strings.Contains(Usage, "bin/brain/search.go") {
+		t.Fatalf("usage must name bin/brain/search.go, got:\n%s", Usage)
+	}
+}
+
 func TestFTSQueryOrdersByScoreDescending(t *testing.T) {
 	if !strings.Contains(FTSStmt, "ORDER BY score DESC") {
 		t.Fatalf("FTS query must order by score DESC, got:\n%s", FTSStmt)
diff --git a/bin/kbsearch/search.go b/internal/brain/search.go
similarity index 92%
rename from bin/kbsearch/search.go
rename to internal/brain/search.go
index 3e090ab..d150186 100644
--- a/bin/kbsearch/search.go
+++ b/internal/brain/search.go
@@ -1,5 +1,6 @@
-// Hybrid FTS + vector search implementation, plus daemon client/server.
-package main
+//go:build cgo && system_ladybug
+
+package brain
 
 import (
 	"bytes"
@@ -18,7 +19,7 @@ import (
 	"time"
 
 	lbug "github.com/LadybugDB/go-ladybug"
-	"github.com/eSlider/2dph/bin/kbsearch/rank"
+	"github.com/eSlider/2dph/internal/brain/rank"
 )
 
 const defaultPort = 17830
@@ -28,7 +29,7 @@ const healthPath = "/health"
 func runSearch(args []string) int {
 	opt, err := rank.ParseArgs(args)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "kbsearch: %v\n%s\n", err, rank.Usage)
+		fmt.Fprintf(os.Stderr, "brain/search: %v\n%s\n", err, rank.Usage)
 		return 2
 	}
 	root, repo, limit, query := opt.Root, opt.Repo, opt.Limit, opt.Query
@@ -247,7 +248,7 @@ func serve(port int) error {
 	})
 
 	addr := fmt.Sprintf("127.0.0.1:%d", port)
-	log.Printf("kbsearch daemon listening on %s", addr)
+	log.Printf("brain search daemon listening on %s", addr)
 	return http.ListenAndServe(addr, mux)
 }
 
@@ -357,3 +358,21 @@ func ensureDaemon(port int) error {
 	}
 	return fmt.Errorf("daemon failed to start on port %d", port)
 }
+
+// Main is the bin/brain/search.go entry: search, serve, or --list-model.
+func Main(args []string) int {
+	if len(args) > 0 && args[0] == "serve" {
+		port := defaultPort
+		if len(args) > 1 {
+			if p, err := strconv.Atoi(args[1]); err == nil {
+				port = p
+			}
+		}
+		if err := serve(port); err != nil {
+			log.Printf("brain/search serve: %v", err)
+			return 1
+		}
+		return 0
+	}
+	return runSearch(args)
+}
diff --git a/bin/kbsearch/types.go b/internal/brain/types.go
similarity index 67%
rename from bin/kbsearch/types.go
rename to internal/brain/types.go
index 509bf1a..09409a9 100644
--- a/bin/kbsearch/types.go
+++ b/internal/brain/types.go
@@ -1,10 +1,9 @@
-// Common types and helpers for kbsearch.
-package main
+package brain
 
 import (
 	"os"
 
-	"github.com/eSlider/2dph/bin/kbsearch/rank"
+	"github.com/eSlider/2dph/internal/brain/rank"
 )
 
 func eps() string { return os.Getenv("KBTEST_EPS") }
diff --git a/bin/kbsearch/yaml.go b/internal/brain/yaml.go
similarity index 99%
rename from bin/kbsearch/yaml.go
rename to internal/brain/yaml.go
index 74c4f18..4bc4e59 100644
--- a/bin/kbsearch/yaml.go
+++ b/internal/brain/yaml.go
@@ -1,5 +1,5 @@
 // YAML emitter ported from bin/kb/yamlout.py — preserves insertion order.
-package main
+package brain
 
 import (
 	"fmt"