# Canon Log — living contract

The canon log is the compact structured state code maintains and injects into
every AI call (charter §11). This is the **contract** the Godot client and the
FastAPI proxy both bind to. The schemas are the single source of truth; this doc
is the human-readable companion.

- Schemas (authoritative): [`/docs/schemas/canon-log.schema.json`](schemas/canon-log.schema.json), [`/docs/schemas/origin.schema.json`](schemas/origin.schema.json)
- Design rationale: [`superpowers/specs/2026-07-09-canon-log-schema-design.md`](superpowers/specs/2026-07-09-canon-log-schema-design.md)

## The three layers

| Layer | Owner | Where | Mutable? |
|---|---|---|---|
| World content | authored | `/content/world` (id-referenced) | no — static per playthrough |
| Origin seed | authored | `/content/origins` | no — an initial-state overlay |
| **Canon log** | **code (client)** | runtime + save | **yes — evolves every turn** |

The client **constructs** the canon log at new-game (origin + world + character
creation) and **maintains** it turn to turn. The proxy never mutates it — it
**validates** every posted log and rejects an invalid one before any prompt work.

## Canon log shape

Full field rules live in `canon-log.schema.json`. Summary:

```json
{
  "schema_version": 1,
  "player":   { "name": "…", "class_id": "sellsword|assassin|priest", "luck_descriptor": "…" },
  "location": { "id": "…", "name": "…" },
  "party":    [ { "id": "…", "name": "…", "disposition": -100..100 } ],
  "recent_events":     ["… (≤5, rolling)"],
  "established_facts": ["… (durable, uncapped)"],
  "active_quests":     [ { "id": "…", "name": "…", "status": "active|complete|failed", "objective": "…" } ],
  "humiliations":      [ { "id": "…", "text": "…", "weight": 1..10, "turn": 0.. } ]
}
```

**The §7 boundary (enforced structurally).** The schema sets
`additionalProperties: false` on the root and on `player`, and `player` admits
only `name`, `class_id`, `luck_descriptor`. **Numeric Luck, stats, HP/MP, and
inventory cannot be represented in the canon log** — the AI never sees a number
it could use to calculate Luck. Only `luck_descriptor` (e.g. "Fortune spits on
you") crosses the boundary.

All string ids match `^[a-z0-9_]+$`.

## Origin seed shape

Full rules in `origin.schema.json`. An origin seeds the initial log:

```json
{
  "schema_version": 1,
  "id": "…", "display_name": "…", "description": "…",
  "start_location_id": "…",
  "situation": ["…"], "opening_facts": ["…"],
  "disposition_overrides": { "<npc_id>": -100..100 },
  "inventory_grants": [ { "item_id": "…", "qty": 1.. } ],
  "start_quest_id": "…|null",
  "build_constraints": { "allowed_classes": ["sellsword",…], "luck_modifier": 0 }
}
```

Every id an origin references must resolve in world content — the proxy exposes
`content.unresolved_refs(origin, world)` for that check; `humiliations` are never
seeded (earned in play).

## API contract

The client posts game state to a role endpoint; the body is:

```json
{ "canon_log": { …a canon log… } }
```

Endpoints (charter §4): `POST /dm/narrate`, `/dm/adjudicate`, `/dm/improvise`,
`/npc/speak`, `/party/banter`. Each validates `canon_log` and, on success,
returns the role's result. (Prompt routing is stubbed for now — a valid log
returns `{"detail": "not implemented"}`.)

### Error shape — ONE envelope for every 422

Whether the log fails the JSON Schema **or** the request body is malformed at the
pydantic layer (missing/mistyped `canon_log`), the proxy returns the **same**
shape, so the client parses one thing:

```json
HTTP 422
{ "detail": { "canon_log_errors": ["<message>", "<message>", …] } }
```

Client rule: on 422, read `detail.canon_log_errors` (a list of strings). It is
never the raw pydantic error list. A degraded-DM fallback (charter §13) should
fire on any non-200 rather than surfacing these strings to the player — they are
for logs and development.

## Per-role injection

The canon log is the shared base of every call; roles add their own extras (the
log never grows per-role fields):

| Role | Log + … |
|---|---|
| Narrator | log only |
| NPC | log + persona, `knowledge[]`, `available_moves[]` (§6) |
| Improviser | log + the whitelisted event-change set (§7) |
| Banter | log, with `humiliations` as primary source (§9) |
| Adjudicator | log + the current legal action set |
