iter 22b.1.4: JOURNAL entry — 22b.1 closed, 22b.2 next

Records the iter close: AST schema floor (Def::Class/Instance) +
workspace registry with three coherence checks (Orphan, Duplicate,
MissingMethod), seven new tests (288 → 295), all three bench gates
green at close. JOURNAL queue updated: 22b.1 closed, 22b.2 next
(typecheck arms + FnDef.type.constraints + class-schema validation).

docs/JOURNAL.md

@@ -10995,3 +10995,189 @@ Not re-run. No runtime, codegen, or check-time path is touched.
 - **21'h, latency methodology, FnDef::synthetic, Boehm full
   retirement, closure-pair slab/pool, deferred richer integration
   paths.** Unchanged from 21'g.
+
+## 2026-05-09 — Iter 22b.1: typeclass schema floor + workspace registry
+
+Trigger: 22b is the typeclass implementer arc queued by 22a. The
+arc is sliced into four sub-iters (22b.1 schema floor + registry,
+22b.2 typecheck arms, 22b.3 monomorphisation, 22b.4 prelude +
+prose-projection arms); 22b.1 is the schema floor. Per the 22a
+queue, the spec is Decision 11 §"Form-A schema" + §"Resolution
+and monomorphisation" (the three coherence checks).
+
+### What 22b.1 shipped
+
+**AST.** `Def::Class(ClassDef)` and `Def::Instance(InstanceDef)`
+landed as additive variants of `Def`. The struct shapes follow
+Decision 11 §"Form-A schema": single-string `param` (multi-param
+classes rejected by shape), optional `superclass: Option<Superclass
+Ref>`, methods carry full FnSig signatures and an
+`Option<Term>` `default` body, instances carry the concrete
+instance type (`Type` variant, not `String`) plus their method
+bodies. Every optional field uses `skip_serializing_if` per the
+13a/19b additive-schema pattern, so canonical-JSON bytes — and
+therefore `def_hash` — of every pre-22b fixture stay bit-identical.
+`iter22b1_schema_extension_preserves_pre_22b_hashes` re-asserts the
+two pinned hashes (`sum.ail.json`/sum → `db33f57cb329935e`,
+`list.ail.json`/IntList → `b082192bd0c99202`); the
+same-shape-different-paths test
+(`iter22b1_classdef_empty_optionals_hash_stable`) asserts that a
+`ClassDef` parsed from JSON without the optional keys hashes
+identically to one constructed with `superclass: None` / `doc:
+None`.
+
+**Downstream `match Def::*` sites.** Every match was extended with
+explicit `Class`/`Instance` arms in `ailang-core` (desugar,
+pretty), `ailang-check` (lib, lift, linearity, uniqueness),
+`ailang-codegen` (lib), `ailang-prose` (lib), `ailang-surface`
+(print), and `crates/ail/src/main.rs` (collect_refs, def_summary).
+Behaviour for 22b.1 is placeholder: skip in typecheck/codegen,
+one-line summary in pretty/manifest, placeholder marker in
+prose/print. Each arm carries a TODO comment naming the
+deferred sub-iter (22b.2 typecheck, 22b.3 codegen, 22b.4
+prose-projection).
+
+**Workspace registry.** `Workspace` gains a `registry: Registry`
+field, populated at the end of `load_workspace` after the import
+DFS. The registry is keyed by `(class-name, type-hash)` where
+`type-hash` is a new `canonical::type_hash(t: &Type) -> String`
+(16-hex prefix, parallel in shape to `def_hash` and `module_hash`).
+`build_registry` enforces three coherence checks per Decision 11
+§"Resolution and monomorphisation":
+
+- **Coherence (orphan-freedom).** Every `instance C T` lives in
+  the module of `C` or in the module of `T`. Otherwise →
+  `WorkspaceLoadError::OrphanInstance` with the class, type,
+  defining module, and the modules where the class and type
+  actually live.
+- **Uniqueness.** No two entries share a key. Otherwise →
+  `DuplicateInstance` with the two colliding modules.
+- **Method completeness.** Each instance specifies a body for
+  every required (non-default) method of its class. Otherwise →
+  `MissingMethod` with the missing method name.
+
+The CLI's `workspace_error_to_diagnostic` carries three new error
+codes (`orphan-instance`, `duplicate-instance`, `missing-method`)
+into the JSON-mode diagnostic stream of `ail check`.
+
+**Test fixtures.** Seven fixtures under `examples/test_22b1_*`:
+
+- `test_22b1_orphan_class.ail.json` — class + instance in same
+  module (positive; one registry entry).
+- `test_22b1_orphan_third_classmod.ail.json` +
+  `test_22b1_orphan_third.ail.json` — class in module A, instance
+  in third module declaring `instance Show Int` (Int is primitive,
+  so neither leg of coherence is satisfied → OrphanInstance).
+- `test_22b1_dup_a.ail.json` + `test_22b1_dup_b.ail.json` +
+  `test_22b1_dup_entry.ail.json` — module A defines class Show
+  + instance Show MyInt (legal, A is class's module); module B
+  defines type MyInt + instance Show MyInt (legal, B is type's
+  module). Entry imports both → DuplicateInstance with two distinct
+  defining modules.
+- `test_22b1_missing_method.ail.json` — class Eq with two
+  non-default methods (eq, ne); instance Eq Int specifies only
+  ne. Fires MissingMethod { method: "eq" }.
+
+The duplicate-instance setup was the trickiest: A→B import
+("class A needs to know type B") works; B does not need to import
+A because the registry build happens over the whole workspace,
+not per-module — B just declares the instance with a string class
+name. No import cycle.
+
+**Deviations from the plan.** The plan in
+`docs/superpowers/plans/2026-05-09-22b.1-typeclass-schema-floor.md`
+prescribed eight commits (one per task). Per the project's
+iter-cadence convention (CLAUDE.md §"Iter cycle"), 22b.1 ships as
+three commits: AST + downstream match arms (22b.1.1), workspace
+registry skeleton + coherence checks + hash-stability tests
+(22b.1.2), fixtures + workspace tests (22b.1.3). The JOURNAL
+update is this commit (22b.1.4).
+
+### Surface round-trip gate
+
+The Form-B parser does not yet know `class` / `instance` head
+keywords (parser arms are deferred to 22b.4 alongside the prose
+projection). The round-trip test
+(`crates/ailang-surface/tests/round_trip.rs`) iterates every
+`examples/*.ail.json` and re-parses the printed text; without
+a filter, `test_22b1_*` fixtures would block the gate on a
+property the schema floor does not promise. The fixture filter
+now excludes `test_22b1_*` until 22b.4 ratifies prose round-trip
+for the new variants.
+
+### Test state
+
+288 → 295 (+7). New tests:
+- `iter22b1_schema_extension_preserves_pre_22b_hashes` (hash.rs)
+- `iter22b1_classdef_empty_optionals_hash_stable` (hash.rs)
+- `iter22b1_workspace_with_no_classes_has_empty_registry`
+- `iter22b1_instance_in_class_module_loads_clean` (positive)
+- `iter22b1_orphan_instance_fires_diagnostic`
+- `iter22b1_duplicate_instance_fires_diagnostic`
+- `iter22b1_missing_method_fires_diagnostic`
+
+All workspace tests in `ailang-check/tests/workspace.rs` and the
+e2e suite remain green; the registry threads through unchanged
+(legacy callers default-construct an empty registry, codepaths
+that hold a real workspace clone the field through).
+
+### Bench gates
+
+All three green at iter close:
+- `bench/check.py` — 63 metrics, 0 regressed, 0 improved, 63 stable.
+- `bench/compile_check.py` — 24 metrics, 0 regressed, 0 improved,
+  24 stable.
+- `bench/cross_lang.py` — 25 metrics, 0 regressed, 0 improved,
+  25 stable.
+
+22b.1 touches workspace-load only; no hot path is exercised. The
+registry-build pass adds two passes over all loaded modules (one
+to collect class/type defining-module maps, one to register
+instances) but only when class/instance defs are present — pre-22b
+fixtures never enter the second pass at all. No measurable impact.
+
+### What 22b.1 does NOT ship
+
+Explicitly deferred to 22b.2:
+- `FnDef.type.constraints` field (constraint annotations on
+  regular fns).
+- Class-schema validation diagnostics: `KindMismatch`,
+  `InvalidSuperclassParam`,
+  `ConstraintReferencesUnboundTypeVar`.
+- Typecheck arms: `MissingConstraint`, `NoInstance`.
+- `OverridingNonExistentMethod`, `MethodNameCollision`.
+
+Deferred to 22b.3:
+- Monomorphisation pass (the only mechanism for class-method
+  calls; replaces resolved class-method calls with synthesised
+  monomorphic FnDefs).
+
+Deferred to 22b.4:
+- Prelude module (`Show`/`Eq`/`Ord` + four primitive instances).
+- `print` rewiring through `Show.show`.
+- Form-B (prose) projection arms for `ClassDef`/`InstanceDef`
+  and the matching parser arms (the round-trip-filter compensation
+  retires when 22b.4 lands).
+
+### JOURNAL queue (updated)
+
+- **22b.2 — typeclass typecheck arms.** `FnDef.type.constraints`
+  schema extension; class-schema validation; `MissingConstraint`
+  + `NoInstance` per call site; `OverridingNonExistentMethod` +
+  `MethodNameCollision`.
+- **22b.3 — monomorphisation pass.** Synthesise monomorphic
+  FnDefs from `(method, type-hash)` pairs; rewrite class-method
+  calls; cache by `(method, type-hash)`. Determines the textual
+  monomorphised-symbol naming (open in 22a).
+- **22b.4 — Prelude + prose round-trip.** Prelude module shipping
+  `Show`/`Eq`/`Ord` and the four primitive instances; `print`
+  rewiring through `Show.show`; Form-B parser/printer arms for
+  ClassDef/InstanceDef; remove the `test_22b1_*` filter from the
+  round-trip gate.
+- **22c — typeclass corpus expansion (deferred).** Unchanged from
+  the 22a queue.
+- **Operator routing through Eq/Ord (deferred, no commitment).**
+  Unchanged from the 22a queue.
+- **21'h, latency methodology, FnDef::synthetic, Boehm full
+  retirement, closure-pair slab/pool, deferred richer integration
+  paths.** Unchanged from 21'g.