---
type: explanation
status: current
related:
  - docs/README.md
  - docs/runbook.md
  - docs/roadmap.md
---

# Design — facts, info, deduction

## Two roots, one transaction

`root` — `facts` | `info` — is a column on every node and edge. Both roots
live in the **same** Ladybug file and are written inside the **same
transaction** (D12). Splitting is semantic, not physical:

- `facts` — assertions backed by ≥2 independent sources (`confidence: confirmed`)
  or marked `partial`/`hypothesis` when the second source is missing.
- `info` — narrative/descriptive leafs (how-tos, READMEs, notes). Searchable,
  never asserted as an answer.

ACID: Ladybug commits facts + info atomically; the audit can treat a snapshot
as one consistent state.

## Deduction search

```
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
     (`web` block from `bin/web/search.go` when no facts hit; status `throttled`
     is not evidence of absence; `--no-web` / `--root` skip it)
```

`--hop N` walks `Leaf-[:FROM_FILE]->File-[:HAS_VERSION]->Commit-[:AUTHORED]->Person`
from each hit (1=File, 2=Commit, 3=Person). Rebuild writes FROM_FILE;
git import writes HAS_VERSION/AUTHORED ([#17](https://git.produktor.io/eSlider/2dph/issues/17)).

Go CLIs parse with **flaggy** via `internal/cli` (D23). Flags may appear
after positionals (`search q --hop 1`). Completions:
`source <(./bin/cli/complete.go bash)`.

## Who / What / How / Where / When + evidence

Every assertion edge carries:

| prop | meaning |
|------|---------|
| who | subject/object persons, services, hosts |
| what | the associated subjects/objects (predicate) |
| how | methods used to read it (compose file? docker ps? ssh config?) |
| where | environment + filesystem path / host |
| when | timestamp / source_rev (git commit, mtime) |
| evidence | ≥2 source refs (compose path, runtime container, config) |
| confidence | confirmed / partial / hypothesis |
| root | facts / info |

## Versioning — nothing is timeless

Content leafs: `sha256`, `observed_at`, `source_rev`, `confidence`. Stale = a
file changed on disk (git HEAD/mtime) after its last observed `source_rev`.
`File-[:HAS_VERSION]->Commit-[:AUTHORED]->Person` records the history of every
content leaf. Commit records come from `bin/git/import.go` (go-git, no git
binary); conversion prints leafs, brain write is `bin/brain/index.go`.

`bin/facts/audit stale` flags leafs whose observed revision is behind the
corpus HEAD.

Fact **interval of truth** (D24 / OQ5): leaf props `valid_from` /
`valid_to` (YYYY-MM-DD, inclusive; empty end = open; both empty = legacy
always-active). `bin/brain/search.go --as-of YYYY-MM-DD` and MCP/HTTP
`as_of` keep hits whose interval covers that day. This is not D16
`temporal_freshness` (source freshness vs HEAD). [#36](https://git.produktor.io/eSlider/2dph/issues/36).
Existing `kb.lbug` without the columns: open/search/add runs an idempotent
`ALTER TABLE Leaf ADD …` (no full rebuild required). Fresh `--rebuild` still
creates them in `CREATE NODE TABLE`.

## Sources (auto-pairing)

- A: runtime state — `docker ps` (container running), ports actually bound
- B: declared config — `docker-compose.yml`, `~/.ssh/config`, `homeserver.yaml`
- C: narrative — READMEs, AGENTS.md, docs

Confirmed = A×B or B×C agreement. Single source = hypothesis + `(not confirmed)`.
Conflicting pairings (≥2 yes vs ≥2 no) stay hypothesis until
`temporal_freshness` or `authority_pairing` fires (`bin/facts/audit contradict`,
[#29](https://git.produktor.io/eSlider/2dph/issues/29)).

## Read path

`bin/brain/get.go`, `stats.go`, and `eval.go` call `internal/brain` with cgo
(`system_ladybug`), compiled by **Zig** (`bin/cgo/zcc`, D21), not gcc.
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
fetches Zig + libs (`bin/cgo/zig`). Incremental write is `bin/kb/add`
(`bin/brain/add.go`). Bulk index/write is still `bin/kb/index`
(`docker compose --profile 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`,
`ingest` (add a leaf; omit body for the CLI hint).
Agents should use these endpoints instead of shebang CLIs.

## Reasoner (D18)

Pluggable OpenAI-compatible URL. RAM: `Qwen/Qwen3.5-9B`. Quality:
`prism-ml/Bonsai-27B-gguf` or `Qwen/Qwen3.6-27B`. No official Qwen3.6-9B.
CPU sidecar: compose profile `reasoner` (`OLLAMA_NUM_GPU=0`,
`127.0.0.1:11435`). Bake-off: `bin/reasoner/bakeoff.go`. Weights stay out
of the 2dph image. See [docs/reasoner.md](reasoner.md).

Gap to v1 (hops, corpus, CI eval): [roadmap](roadmap.md),
[epic #16](https://git.produktor.io/eSlider/2dph/issues/16).