Pre-publish review #008: gate int_keys on canonical keys, restore no-prealloc array rule

Review #008 (docs/reviews/008-pre-publish-review.md) audits the two
post-#007 unreviewed commits (dea96f0 bench port, d4635d2 perf) before
the first crates.io publish of 0.3.0.

- F1: the int_keys integer dispatch accepted non-canonical mapping
  keys ("01", "+1" parse as u64 1) — the reader dispatched disc 1
  while the materializer, validation plan, and tunion rejected the
  same buffer. compile_int_keys now builds the table only when every
  key is canonical (v.to_string() == key); otherwise the string
  fallback applies (agreement restored, perf kept for canonical
  mappings). Tests: r8_non_canonical_mapping_key_disables_int_dispatch,
  r8_canonical_mapping_keys_keep_int_dispatch.
- F2: d4635d2 reintroduced Vec::with_capacity(count) on both array
  materializers. Bounded per array by MAX_ARRAY_ELEMENTS but nesting
  compounds: probe (counting allocator) measured ~477 MB simultaneous
  allocation from a ~1 KB schema + empty buffer (100-level stride-0
  chain, all legal under the caps). H1's layer-1 rule restored:
  Vec::new() + push. Bench unchanged (packet read 220µs vs 246µs
  baseline). Test: r8_deeply_nested_stride0_array_rejects_before_bulk_prealloc.
- N3a disposition (review #007's deferred item): BastField::synthetic
  (pub(crate), zero callers, #[allow(dead_code)]) deleted; the seven
  source() accessors are public API and stay (semver decision —
  removal needs an explicit ask); resolve_typeref_as_def's inline
  struct/union/enum arms probe-verified reachable (inline struct
  union variants are legal) — kept.
- CHANGELOG: 0.3.0 entry (compiled forms, breaking surface, hardening
  fixes, coverage). README: ReadPlan/ValidationPlan roles, union
  conventions, untrusted-schema bounds.

Verification: 569 tests green (491 lib + 17 + 34 + 15 + 12, + 2
ignored doctests), clippy -D warnings clean, cargo doc 0 warnings,
wasm32 build green, cargo publish --dry-run clean.

README.md

@@ -24,10 +24,11 @@ A BAST document serves three roles simultaneously:
 
 | Role | Mechanism | When |
 |------|-----------|------|
-| **Validation spec (bytes)** | BAST-native validator (recursive walker over the BAST type tree) | Access time (`validate_bytes`) |
+| **Validation spec (bytes)** | Compiled `ValidationPlan` walk over the materialized `Value` (ADR-012) | Access time (`validate_bytes`) |
 | **Validation spec (JSON)** | Standard `jsonschema::Validator` from a consumer-provided JSON Schema | Load time (build validator), access time (`validate_json`) |
 | **Layout spec** | Offset computation from type sizes + field order | Load time (build offset map / packed layout) |
 | **Data access** | Read/write at computed offsets | Access time (read field, write field) |
+| **Wire access (packed)** | Compiled `ReadPlan` (ADR-011) — compile-once, no per-read schema walk | Access time (`SequentialReader`) |
 
 No separate format definition, no separate parser, no separate
 validator. The BAST document is the single source of truth for the
@@ -159,11 +160,16 @@ same BAST document can be compiled in either mode. Decided in ADR-002.
 - **Byte-offset** — a fixed-size integer (`uint8`/`uint16`/`uint32`) at
   a known byte offset. The SFTP `Packet` pattern: byte 0 is the type
   byte, bytes 1..N are the variant struct. Mapping keys are stringified
-  integers.
+  integers. With all-canonical numeric keys the compiled reader
+  dispatches on the raw integer (no per-read stringification).
 - **Field-name** — a named field within the union. The TypeBox
   `typedef.ts` pattern. Mapping keys are string values matching the
   discriminator field's value. The `fields` array declares the
-  discriminator field (D-BAST-005).
+  discriminator field (D-BAST-005), which must be its first entry; the
+  variant must not re-declare it or any shared field. The builder lays
+  out the declared `fields` first, then the variant's own fields
+  (ADR-011 addendum) — builder, reader, materializer, and validator all
+  agree on that convention.
 
 Variant `$ref`s are resolved lazily — no compile-time inlining step.
 
@@ -182,10 +188,10 @@ types (ADR-VAL-SPLIT):
 
 - `validate_bytes(&[u8])` — for raw byte buffers (channels' chunk
   header, SFTP packets). Materializes a `Value` tree from the bytes via
-  the layout engine, then runs the **BAST-native validator** — a
-  recursive walker over the BAST type tree that checks the value-domain
-  constraints the materializer doesn't (integer ranges, `maxLength`,
-  enum index bounds, union variant constraints). No
+  the layout engine, then runs the compiled **`ValidationPlan`** (0.2.0
+  used an interpretive BAST walker; 0.3.0 compiles the value-domain
+  constraints — integer ranges, `maxLength`, enum index bounds, union
+  variant dispatch — once at compile time). No
   `jsonschema` involvement; the BAST document is the complete
   validation spec for bytes (D-BAST-006).
 - `validate_json(&Value)` / `is_valid_json(&Value)` — for already-parsed
@@ -244,6 +250,15 @@ code was converted to `Err` ahead of v0.1.0 (review #002, L2); the
 BAST parser preserves this invariant — overflow-safe arithmetic
 (`checked_add`, `usize::try_from`) on all offset/count casts.
 
+0.3.0 adds compile-time bounds for adversarial schemas: array counts
+≤ 2^16 elements, computed array sizes ≤ 2^26 bytes, `align` ≤ 4096,
+`maxLength` ≤ 2^26, and a shared reference-graph guard that rejects
+cyclic `$ref`s and >128-deep nesting in every public schema walker.
+Adversarial buffers fail with `Access` errors at read time — the
+materializers never preallocate from declared counts. Reviews #006,
+#007, and #008 document the audit trail
+([docs/reviews/](docs/reviews/)).
+
 ## Documentation
 
 Architecture documentation lives under [`docs/architecture/`](docs/architecture/):