rose-ash/plans/mod-on-sx.md

# mod-on-sx: Moderation on Prolog

rose-ash needs moderation infrastructure: reports flagged by users, automated
classifications (spam, abuse), tiered escalation (auto → human → appeal), audit
trails. Each decision is the conclusion of a backtracking search over evidence and
policy rules — exactly what Prolog does.

Where acl-sx says "may this happen?", mod-sx says "should this stay?" The former is
a positive decision (proof of grant); the latter often a negative one (proof of
violation), and policy chains naturally backtrack: if the first rule doesn't apply,
try the next.

End-state: a Prolog-on-SX layer for moderation policy declaration and evaluation,
with persistent report lifecycle, audit log, escalation state machine, and
federation extension.

## Status (rolling)

`bash lib/mod/conformance.sh` → **106/106** (Phases 1–3 complete)

## Ground rules

- **Scope:** only touch `lib/mod/**` and `plans/mod-on-sx.md`. Do **not** edit
  `spec/`, `hosts/`, `shared/`, `lib/prolog/**`, or other `lib/<lang>/`. You may
  **import** from `lib/prolog/` (public API in `lib/prolog/prolog.sx`); do **not**
  modify Prolog.
- **Shared-file issues** go under "Blockers" with a minimal repro; do not fix here.
- **SX files:** use `sx-tree` MCP tools only.
- **Architecture:** policies are Prolog rules over `report(...)` and `evidence(...)`
  facts. Decisions are query results. Proof trees become audit records. The state
  machine for report lifecycle is separate (an SX module on top).
- **Shared with acl-sx:** rule-engine plumbing may be liftable into `lib/guest/`.
  Watch for it; flag in Progress log but do not extract until both subsystems are
  past Phase 2.
- **Commits:** one feature per commit. Keep Progress log updated and tick boxes.

## Architecture sketch

```
Report                                  Decision
  {:by :about :reason :at}                {:action :proof :next-state}
        │                                       ▲
        ▼                                       │
lib/mod/schema.sx                       lib/mod/engine.sx
  — report/4, evidence/2,                 — query Prolog with report fact
    classification/3 predicates             — extract proof tree
        │                                       ▲
        ▼                                       │
lib/mod/policy.sx                       lib/mod/lifecycle.sx
  — rule syntax → Prolog                  — state machine
  — action heads:                         — open → triaged → decided
    {:keep :hide :remove                  — appeal handling
     :escalate :ban}                            │
        │                                       ▼
        ▼                                lib/mod/audit.sx
lib/mod/api.sx                            — append-only decision log
  — (mod/report ...)                      — proof tree persistence
  — (mod/decide report)                   — query API
  — (mod/appeal id)
        │
        ▼
lib/mod/fed.sx
  — cross-instance reports via fed-sx
  — decision sharing / trust model
```

## Phase 1 — Report representation + simple policy

- [x] `lib/mod/schema.sx` — `report(id, by, about)`, `classification(id, kind)`,
  `report_count(subject, n)` Prolog facts; keyword classifier derives evidence
- [x] `lib/mod/policy.sx` — `mod/mk-rule` + ordered `mod/default-rules`; conditions
  (`:classification`, `:count-at-least`) compile to Prolog goals; `policy_action/3`
  clauses, last clause `true` so every report yields at least `:keep`
- [x] `lib/mod/engine.sx` — `(mod/decide-report r reports rules)` queries
  `policy_action(Id, Action, Rule)` with `pl-query-one` (clause order = precedence);
  returns a decision dict `{:action :rule :report-id :proof}` carrying the why
- [x] `lib/mod/api.sx` — registry + `(mod/report by about reason)`, `(mod/decide id)`
- [x] `lib/mod/tests/decide.sx` — 31 cases: spam/abuse keyword, repeated→escalate,
  no-rule→keep, precedence (spam beats repeated), proof shape, registry ids
- [x] `lib/mod/scoreboard.{json,md}`
- [x] `lib/mod/conformance.sh`

## Phase 2 — Evidence + audit trail

- [x] evidence accumulation — `report :evidence` list; `mod/attach-evidence` +
  api `mod/add-evidence`; asserted as `evidence(Id, 'kind', 'val')` facts;
  new `:evidence` condition + `reviewer-remove` rule consume it
- [x] proof tree from Prolog derivation — `mod/proof-goals` re-queries each body
  goal (id bound) against the same DB, recording goal text, solved?, and the
  bindings that satisfied it (e.g. count goal yields N=3, S=subject)
- [x] `lib/mod/audit.sx` — append-only log: monotonic `:seq`, decision + proof +
  evidence snapshot; never mutates prior entries
- [x] `(mod/audit id)` retrieval (+ `mod/audit-latest`, `mod/audit-all`, count)
- [x] `lib/mod/tests/audit.sx` — 29 cases: proof goal text/bindings, evidence-driven
  decisions, append-only ordering, per-report retrieval, snapshot-at-decision-time

## Phase 3 — Escalation + lifecycle state machine

- [x] state machine: `lib/mod/lifecycle.sx` — `:open → :triaged → :decided →
  :appealed → :final` as a pure SX module over the engine; transition table guards
  illegal moves (sets `:error`, leaves state); immutable cases with `:history`
- [x] auto-tier: `mod/case-triage` runs the engine; terminal action (hide/remove/
  keep) → tier `auto`, `mod/case-resolve` advances to `:decided`
- [x] human-tier: `:escalate` action → tier `human`; `mod/case-resolve` is blocked
  (sets `:error`); `mod/case-review` attaches evidence, re-decides, advances
- [x] appeal: `mod/case-appeal` attaches appeal evidence + re-runs the engine; new
  `exonerated-keep` rule (top precedence) lets exoneration override a prior `:hide`
- [x] `(mod/appeal id new-evidence)` API — lifecycle façade over a case registry in
  api.sx (`mod/triage` / `resolve` / `review` / `appeal` / `finalize`), logging
  each committed decision to the audit trail
- [x] `lib/mod/tests/escalation.sx` — 46 cases: transition guards, auto/human tiers,
  blocked resolve, full appeal-override traversal, history, api façade

## Phase 4 — Federation

- [ ] cross-instance reports — peer raises report about local content (or vice versa)
- [ ] decision sharing — actions taken locally propagate to peers via fed-sx
- [ ] trust model — peer's decision is advisory unless `(trust peer :mod)` is granted
- [ ] revocation — undo applied moderation if proof was invalidated
- [ ] `lib/mod/tests/fed.sx` — federated decision chains (mock fed-sx in tests)

## Progress log

- **Phase 3 complete — 106/106** (+46 escalation). Lifecycle state machine,
  auto/human tiers, appeal-override, and an api façade. The state machine is a
  pure SX module (`lib/mod/lifecycle.sx`) over the engine — policy stays in
  Prolog, lifecycle stays out of it, per the design constraint. Cases are
  immutable values threaded through transitions; illegal moves set `:error`
  rather than throwing (the env's error handling is untested, so this keeps tests
  deterministic). Tier logic: triage runs the engine, an `:escalate` action parks
  the case at the human tier where `mod/case-resolve` is blocked until
  `mod/case-review` supplies evidence. Appeal-override works because the new
  `exonerated-keep` rule sits at top precedence — appeal evidence re-runs the same
  engine and a higher-precedence clause wins. The api façade (`mod/triage` …
  `mod/finalize`) keeps a per-report case registry and logs each committed
  decision to the Phase-2 audit trail, so lifecycle + audit compose.
  - **Gotcha:** `sx_insert_near` inserts only the FIRST top-level form of a
    multi-form source — silently drops the rest (byte count barely changes). For
    multi-form additions, rewrite the file with `sx_write_file`.
- **Phase 2 complete — 60/60** (+29 audit). Evidence accumulation, constructive
  proof trees, append-only audit log. A decision's `:proof :goals` is a real
  derivation: each body goal is re-queried against the same Prolog DB with the
  report id bound, so the count rule's proof carries `N=3, S=<subject>` straight
  from unification — not a reconstruction. Evidence is asserted as
  `evidence(Id, 'kind', 'val')`; the new `reviewer-remove` rule (placed first =
  highest precedence) lets human review override automated classification.
  `mod/decide` now commits each decision to the audit log with the evidence
  snapshot in force at decision time. Unknown predicates in this Prolog fail
  gracefully (verified) — so an evidence-less report safely falls through the
  reviewer rule without an existence error.
  - **Liftable (acl-sx watch):** the proof-tree builder (`mod/proof-goals` —
    re-query-each-goal) and the append-only log shape are both generic. Both
    subsystems are now past Phase 2; next time either touches plumbing, evaluate
    lifting `proof-goals` + the audit-log primitives into `lib/guest/`.
- **Phase 1 complete — 31/31.** Report schema, keyword classifier, policy DSL,
  engine, registry api, conformance harness. Decisions are proofs: each carries
  `:rule` (matching clause), `:proof {:rule :conditions :evidence :count}`.
  Precedence is Prolog clause order resolved by `pl-query-one`; a trailing
  `true`-bodied default rule makes "no rule matched" a real `:keep`, not a query
  failure. Evidence (spam/abuse classification) derived in SX and asserted as
  `classification/2` facts; repeated-report escalation uses a genuine Prolog
  join + arithmetic (`report(Id,_,S), report_count(S,N), N >= 3`).
  - **Gotcha (env):** loading the prolog libs strips `includes?` (and other
    high-level string prims) from the eval env — only the set the prolog
    tokenizer itself uses survives (`slice`, `len`, `nth`, `=`, `join`,
    `downcase`, `map`, `reduce`, `append!`). Implemented `mod/str-contains?` over
    `slice`/`len` rather than relying on `includes?`. Watch for this in later
    phases — stick to the blessed primitive set.
  - **Liftable (acl-sx watch):** `mod/join-with`, `mod/str-contains?`, `mod/any?`,
    and the rule→clause compilation shape are generic rule-engine plumbing. Do not
    extract to `lib/guest/` until both mod-sx and acl-sx are past Phase 2.

## Blockers

(none)