157 lines
9.1 KiB
Markdown
157 lines
9.1 KiB
Markdown
# Game Kernel — specification and acceptance metrics
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Status: **v0.1 draft** — implements ADR-0002 (reimplement in Rust,
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assimilate patterns). Governs crates `cb-kernel`, `cb-events`,
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`cb-game-runtime`, and the first game package `games/ground`.
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Baselines referenced: research/CB-RES-0001-game-kernel.md.
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Instruments: specs/MetricsAndScenarios.md. Rules content:
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specs/GroundRules.md.
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The kernel is the **authoritative semantic layer** of the Clay-Borg
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architecture (Blueprint §1): headless, deterministic, replayable. No
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rendering, no physics, no networking — those attach later through ports
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and must never leak types into anything specified here (M-D4-LEAK = 0).
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---
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## 1. Crate boundaries
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| Crate | Owns | Must not know about |
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|---|---|---|
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| `cb-kernel` | canonical IDs, RNG service, command/event/fold traits, clock-free tick model | any concrete game, serialization format details |
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| `cb-events` | event envelope, append-only log, snapshots, canonical serialization, state hashing | game semantics |
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| `cb-game-runtime` | round/phase machinery, simultaneous commit windows, per-player projections, scenario-runner API | GROUND specifics |
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| `games/ground` | GROUND rules: state aggregate, commands, events, reducers per specs/GroundRules.md | anything below `cb-game-runtime`'s public API |
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Dependency rule: `games/ground → cb-game-runtime → cb-events → cb-kernel`.
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No cycle, no skip that bypasses a public API. External crates allowed in
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the headless kernel workspace: serde (+format crate), a seedable RNG
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(e.g. chacha), a hash (sha2), thiserror-class error derive — target total
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transitive crates ≤ 20 (AM-4).
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## 2. Canonical model
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### 2.1 Identifiers (`cb-kernel`)
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Newtyped, copyable, ordered: `GameId`, `PlayerId`, `EntityId`
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(problems, tokens, relations), `CommandId`, `EventId` (monotonic
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`u64` sequence per game), `Seed` (`u64`). No UUIDs inside the hot
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path; string forms only at the boundary.
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### 2.2 The mutation pipeline (assimilated: cqrs-es pattern)
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```text
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Command (actor-tagged intent)
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→ validate(&State, &Command) → Result<Vec<Event>, Rejection>
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→ fold(&mut State, &Event) # infallible, total
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→ EventLog::append(events) # with per-event hash chaining
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```
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- **K1** All state change flows through events; there is no other mutator.
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`fold` is infallible: every validation that could fail happens in
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`validate`, so a logged event always applies.
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- **K2** Commands carry: `CommandId`, issuing `PlayerId` (or `System`),
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round number, and payload. Duplicate `CommandId` within a game is
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rejected (idempotency).
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- **K3** Rejections are typed and testable (`Rejection::StressGate`,
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`::NotYourTarget`, `::SlotOccupied`, …); scenarios assert on them
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(`expect.rejects`).
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- **K4** Events are closed enums per game package, serialized through a
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versioned envelope: `{seq, game_id, round, kind, payload, schema_ver}`.
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### 2.3 Determinism (assimilated: Rune's enforced discipline)
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- **K5** The only randomness source is the kernel RNG service, seeded from
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`Seed`; RNG draws are themselves events (or deterministically derived
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from the event sequence) so replay never re-rolls.
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- **K6** No ambient time, no OS entropy, no pointer/hash iteration order:
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all iterated collections in semantic state are ordered (`BTreeMap`/
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`Vec`); `HashMap` is forbidden in `games/*` state. Enforced by lint/deny
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in CI, not convention (AM-8).
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- **K7** State hash = SHA-256 over the canonical serialization of the
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aggregate; computed on demand and recorded at round End events.
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- **K8** Double-run invariant: the scenario runner executes every scenario
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twice with the same seed and fails on any hash divergence
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(MetricsAndScenarios §2).
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### 2.4 Snapshots and replay (`cb-events`)
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- **K9** A snapshot is the canonical serialization of the full aggregate +
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the `EventId` it includes. `snapshot + remaining events → state` must be
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hash-identical to a from-genesis fold (AM-7).
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- **K10** A replay bundle (`.cbreplay`, MetricsAndScenarios §4) contains
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manifest, command log, initial snapshot, and failed expectations; the
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runner's `--replay` re-executes it bit-identically.
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- **K11** Log format is append-only, length-prefixed, versioned; a
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truncated tail is detected, not silently accepted.
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### 2.5 Simultaneity and hidden information (`cb-game-runtime`)
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- **K12** Commit window primitive (assimilated: GROUND's Select/Reveal,
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boardgame.io `activePlayers` shape): the runtime opens a window naming
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the players who must submit; submissions are recorded as **commitment
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events** whose payload is hidden in projections until the window's
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reveal event; late/duplicate submissions are Rejections.
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- **K13** Projection (assimilated: OpenSpiel information states): for each
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`PlayerId` (and `Spectator`), a total function `project(&State) →
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PlayerView` that structurally cannot include: other players' unrevealed
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commitments, face-down problem identities, other players' hands.
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Projections are derived views — never inputs to `validate`/`fold`.
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- **K14** The GROUND round (GR-R01..R09) is expressed through runtime
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primitives: one commit window per Select, reveal, then fixed-order
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resolution steps with Lead-order iteration (GR-R06/R07) driven by
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system commands.
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### 2.6 GROUND aggregate (`games/ground`)
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- **K15** State implements specs/GroundRules.md §1 exactly; every GR-rule
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is realized in `validate`/`fold` and cross-referenced by rule ID in doc
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comments, giving a greppable rule→code→scenario chain.
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- **K16** U-item defaults (GroundRules §Underdetermined) are implemented
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behind clearly named functions so a ground-game ruling is a localized
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change; their scenarios carry `provisional: true`.
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## 3. Scenario runner and CLI surface
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- **K17** `cb-game-runtime` exposes the scenario runner as a library; a
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thin binary (`cb-sim`, precursor of `cb sim`) runs
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`scenarios/ground/*.yaml` per MetricsAndScenarios §2: setup presets,
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ordered actor-tagged commands, partial end-state assertions, `covers`,
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`rejects`, optional `state_hash`.
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- **K18** Benchmarks are Criterion benches driving the same scenario
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format at scale (MetricsAndScenarios §3); the synthetic workload
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mirrors the CB-RES-0001 harness shape (3 players, commit/reveal
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rounds) for same-shape comparison.
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---
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## 4. Acceptance metrics (the code loop's exit condition)
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Per InnerLoop step 4/5: T08 iterates until every row meets its target;
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evidence lands in `evidence/CB-EV-0001-game-kernel.md` with no
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`unmeasured`. Baselines from CB-RES-0001; cited-only rows cap at parity.
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| ID | Metric | Baseline (CB-RES-0001) | Target | Verdict basis |
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|---|---|---|---|---|
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| AM-1 | M-D1-COV: GR-rules covered by ≥1 passing scenario | no candidate has any (observation) | **100%** of GR + U rules | measured by runner report |
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| AM-2 | M-D1-SPL: spec lines per rule in `games/ground` rules code (impl LOC ÷ rule count) | boardgame.io ~36 LOC for the 2-move synthetic game | ≤ 40 LOC/rule, paired with AM-1 (anti-gaming pair) | measured (tokei + rule count) |
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| AM-3 | Synthetic-workload definition size: LOC to express the CB-RES-0001 synthetic game on our kernel | ~36 LOC (boardgame.io, measured) | ≤ 50 LOC | measured |
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| AM-4 | M-D2-DEP: transitive crates, headless workspace | 120 npm packages | **≤ 20** | measured (cargo tree) |
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| AM-5 | M-D2-BLD: clean release build of headless workspace | n/a (npm install ~seconds; not comparable) | ≤ 60 s on bnt-lap001, recorded not gated | measured |
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| AM-6 | M-D3-THR: applied events/s, synthetic workload, same machine | boardgame.io ~1,100–1,900 moves/s (best config, degrading) | **≥ 100,000/s** (stipulated target, ADR-0002) | measured |
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| AM-7 | M-D3 scaling: throughput @100k events vs @5k; and snapshot+replay of 100k events | boardgame.io 0.45–0.66× @20–40k, DNF @100k | **≥ 0.9×** (flat), replay of 100k events ≤ 5 s, hash-identical | measured |
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| AM-8 | Determinism invariant: N=10 same-seed replays, bit-identical hashes; HashMap-in-state deny lint clean | Rune: enforced by tooling (cited) | zero divergence, lint clean in CI | measured (invariant, not a verdict row) |
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| AM-9 | M-D3-MEM: peak RSS, 100k-event synthetic run | boardgame.io ~100→232 MB @5k→40k (indicative) | ≤ 64 MB, flat with history given snapshot interval | measured (indicative label, same method) |
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| AM-10 | M-D4-LEAK: foreign types in `cb-*-api`-visible signatures | boardgame.io: JS-ecosystem-locked | **0** | measured (grep/deny rule) |
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| AM-11 | M-D4-SWAP: null + reference impls passing one conformance suite | no candidate has the pattern | RNG and log storage each have ≥2 impls (real + test/null) under one suite | measured (bool) |
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| AM-12 | M-D2-TOK / M-D2-CST: tokens and USD per completed task | n/a — first pass sets our own baseline | recorded per task in the evidence cost log (price sheet 2026-07-31) | recorded, not gated |
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Comparisons against the event-sourcing 10⁵–10⁶/s estimate stay **parity**
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until a local Rust comparator is measured (open follow-up from the
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adversarial review).
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## 5. Out of scope for this pass
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Networking/session protocol, WIT/Wasm game boundary, ECS world layer,
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rendering, persistence beyond file snapshots, host migration, and any
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second game. Each arrives through its own loop pass with its own survey.
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