feat: DuckDB quantiles in-process (gcc CGO), not Ladybug. (#34)

OQ3: internal/duckstats + bin/qa/stats.go. Zig stays Ladybug-only.
mikefarah/yq for small structured slices. Gitea #30.

skills/duckdb/SKILL.md

@@ -0,0 +1,38 @@
+---
+name: duckdb
+description: >-
+  Use https://github.com/duckdb/duckdb-go in-process for columnar analytics
+  (quantiles, GROUP BY, JSON/CSV/Parquet/JSONL scans) when that is faster than
+  nested Go loops. Not Ladybug. Not the web-search sqlite cache. Use when
+  aggregating samples, counting JSONL, or SQL over tabular files.
+---
+
+# duckdb-go
+
+Use https://github.com/duckdb/duckdb-go where it makes sense to get better performance in code.
+
+In-process DuckDB (`internal/duckstats`, `database/sql` driver `duckdb`).
+Vectorized SQL over tables, JSONL, CSV, Parquet. CGO with bundled libs
+(linux/darwin amd64/arm64). Links with **gcc/g++** (libstdc++), not Zig.
+D21 Zig (`bin/cgo/zcc`) is Ladybug/tokenizers only. After
+`eval "$(bin/cgo/zig env)"`:
+
+```bash
+CC=gcc CXX=g++ CGO_CFLAGS= CGO_LDFLAGS= ./bin/qa/stats.go <<< '[1,2,3,4,5]'
+CC=gcc CXX=g++ CGO_CFLAGS= CGO_LDFLAGS= go test ./internal/duckstats
+```
+
+| Store | Job |
+|-------|-----|
+| Ladybug | graph + FTS + HNSW (facts/info) |
+| modernc sqlite | web-search KV cache + throttle |
+| duckdb-go | OLAP: quantiles, counts, scans of many rows/files |
+| mikefarah/yq | small YAML/JSON/XML/CSV/TOML/HCL slice, not bulk |
+
+```bash
+./bin/qa/stats.go <<< '[1,2,3,4,5]'
+./bin/qa/stats.go --jsonl path/to/rows.jsonl
+```
+
+Do not open Ladybug through DuckDB. Do not put secrets or client PII into
+DuckDB files under the repo.

skills/picoclaw/SKILL.md

@@ -1,15 +1,15 @@
 ---
 name: picoclaw
 description: >-
-  2dph is the memory/fact gate, not the agent loop. Use when wiring PicoClaw
-  or any MCP client: call brain search/get/audit before a factual reply.
-  throttled is not a negative finding.
+  2dph is the memory/fact gate. Compose runs the official PicoClaw gateway.
+  Use when wiring PicoClaw or any MCP client: call brain search/get/audit
+  before a factual reply. throttled is not a negative finding.
 ---
 
 # PicoClaw — fact-check before assert
 
-PicoClaw (or any agent) speaks MCP at `POST /mcp` on `bin/brain/serve.go`.
-2dph does not run the agent loop. Compose: `docker compose --profile picoclaw up brain-mcp`
+PicoClaw speaks MCP at `POST /mcp` on `bin/brain/serve.go`. Compose profile
+`picoclaw` runs the official `sipeed/picoclaw` gateway plus `brain-mcp`
 (see [docs/picoclaw.md](../../docs/picoclaw.md)).
 
 ## Tool order (before a factual reply)

skills/postgres/SKILL.md

@@ -9,7 +9,7 @@ description: >-
 # postgres
 
 `bin/postgres/query.go` wraps vendored `bin/db/psql-yq`. Output is YAML
-(cheaper than psql ASCII, easy to slice with `yq`).
+(cheaper than psql ASCII, easy to slice with mikefarah/yq).
 
 ```bash
 bin/postgres/query.go --profile onlyoffice -s document_asset   # column list

skills/web-search/SKILL.md

@@ -11,7 +11,7 @@ description: >-
 ```bash
 bin/web/search.go "LadybugDB vector index"
 bin/web/search.go "model2vec multilingual" --category it
-bin/web/search.go "hypervisor" --site example.com --json | jq -r '.results[].url'
+bin/web/search.go "hypervisor" --site example.com --json | yq -r '.results[].url'
 bin/web/search.go "postgres partial index" --lang en --fresh year
 ```
 

skills/web-search/reference/instance-tuning.md

@@ -43,7 +43,7 @@ found" unless the client refuses to call it absence.
 
 ```bash
 for i in $(seq 10); do
-  bin/web/search.go "test $i" -n 1 --refresh --json | jq -r .status
+  bin/web/search.go "test $i" -n 1 --refresh --json | yq -r '.status'
 done
 ```
 

skills/yq/SKILL.md

@@ -0,0 +1,33 @@
+---
+name: yq
+description: >-
+  Use https://github.com/mikefarah/yq to work with YAML, JSON, XML, CSV,
+  TOML, HCL where it's efficient and less code. Use when slicing compose,
+  config, --json tool output, CSV/TOML/HCL/XML, or converting between those
+  formats. Not kislyuk Python yq. Not jq when yq already does the job.
+---
+
+# yq (mikefarah)
+
+Use https://github.com/mikefarah/yq to work with YAML, JSON, XML, CSV, TOML, HCL where it's efficient and less code.
+
+This is the Go `yq` (`yq --version` contains `mikefarah`). It is not
+kislyuk/yq (Python, jq-syntax, YAML-only wrapper). `bin/db/psql-yq` already
+calls this binary.
+
+Prefer `yq` over `python3 -c`, `jq`, or ad-hoc parsers when one expression
+reads or converts the file. Keep Python/Go for HTTP, binary protocols, and
+in-process tests.
+
+```bash
+yq '.services.picoclaw.image' compose.yaml
+yq -P . deploy/picoclaw/config.json          # JSON → YAML
+yq -o=json '.gates'                           # JSON stdin (qa/system_perf.py --json)
+yq -p=csv -o=json .
+yq -p=xml -o=json .
+yq -p=toml '.package.name' file.toml
+bin/brain/search.go "LadybugDB" --json | yq '.[].ref'
+bin/web/search.go "hypervisor" --json | yq -r '.results[].url'
+```
+
+Do not print secrets, PII, or `$HOME/.config/brain/` through `yq`.