M3a task 01: copy a strict.rs of its own

The strict.rs in files/ is the merged one and walks task 02's new wire
fixtures, so task 01's gate could not pass; the first run stopped on it.
Task 01 now copies area A's version, checked to give 3 and 5 passed at
task 01's end state.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/plans/M3a/01-proto-audit-types.md

@@ -12,7 +12,8 @@ nothing else in the workspace changes.
 
 ## Files
 
-- Copy: `crates/proto/tests/records.rs`, `crates/proto/tests/strict.rs`,
+- Copy: `crates/proto/tests/records.rs`, `crates/proto/tests/strict.rs` (from
+  `files/crates/proto/tests/strict.rs-task01`; `files/.../strict.rs` is task 02's),
   `crates/proto/tests/fixtures/records/audit.jsonl`
 - Modify: `crates/proto/src/audit.rs`, `crates/proto/src/lib.rs`, `docs/implementer-log.md`
 
@@ -92,7 +93,7 @@ In `lib.rs` the audit export becomes
 ## Steps
 
 - [ ] **1. Copy.** `git switch -c m3a`, then
-  `cp docs/plans/M3a/files/crates/proto/tests/records.rs docs/plans/M3a/files/crates/proto/tests/strict.rs crates/proto/tests/`
+  `cp docs/plans/M3a/files/crates/proto/tests/records.rs crates/proto/tests/ && cp docs/plans/M3a/files/crates/proto/tests/strict.rs-task01 crates/proto/tests/strict.rs`
   and `cp docs/plans/M3a/files/crates/proto/tests/fixtures/records/audit.jsonl crates/proto/tests/fixtures/records/`
 - [ ] **2. See the tests fail.** `cargo test -p proto --test records`. Expected: it does not
   compile (`AuditEvent` is not found).

docs/plans/M3a/README.md

@@ -39,7 +39,7 @@ tip T17) and what that check exposed. The detail is in `checks-a.md` to `checks-
 
 | # | File | Delivers | Tests that define it | Check | What the check exposed |
 |---|---|---|---|---|---|
-| 01 | `01-proto-audit-types.md` | `AuditRecord`, `AuditEvent`, `DecisionRecord` and friends | `proto/tests/records.rs`, `strict.rs`, `fixtures/records/audit.jsonl` | reference (the types) | `DecisionRecord`'s unit variants accepted unknown fields (serde ignores `deny_unknown_fields` there); found by `strict.rs` |
+| 01 | `01-proto-audit-types.md` | `AuditRecord`, `AuditEvent`, `DecisionRecord` and friends | `proto/tests/records.rs`, `strict.rs`, `fixtures/records/audit.jsonl` | reference (the types) | `DecisionRecord`'s unit variants accepted unknown fields (serde ignores `deny_unknown_fields` there); found by `strict.rs`. After hand-over: the merged `strict.rs` named task 02's fixtures, so task 01's gate could not pass (fixed with `strict.rs-task01`) |
 | 02 | `02-proto-admin-wire.md` | the admin messages, `u64` approval ids, `approval_pending`, `tool_denied` | `wire.rs`, `turn_wire.rs`, `admin_wire.rs`, `strict.rs`, 17 wire fixtures | reference (the types) | the same serde hole, found independently; serde's array form for structs (left open in `decisions.md`) |
 | 03 | `03-proto-chain-verifier.md` | `ChainVerifier`, `ChainReport` | `proto/tests/chain.rs`, 30 fixture logs with real hashes | reference, generated fixtures, 8 mutants | four spec gaps: which `seq` the lists report, the resumed verifier inside a failed region, a `Recovery` describing nothing, the report fields a writer needs |
 | 04 | `04-brokerd-config.md` | `brokerd.toml` into `Config` | `brokerd/tests/config.rs`, 6 fixtures | minimal reference | socket paths when only `home` is set; stale "Used by" column in `dependencies.md` |
@@ -64,7 +64,9 @@ tip T17) and what that check exposed. The detail is in `checks-a.md` to `checks-
 
 `files/` holds everything the tasks copy in, byte-identical to the reference tree
 (`~/src/boxmaker-ref`, branch `m3a-ref`, unpushed). `files/Makefile-task21` is task 21's
-`Makefile`; `files/Makefile` is task 22's, with the end-to-end line.
+`Makefile`; `files/Makefile` is task 22's, with the end-to-end line. Likewise
+`files/crates/proto/tests/strict.rs-task01` is task 01's `strict.rs`; `files/.../strict.rs` is task
+02's, which also walks task 02's new wire fixtures.
 
 **State of the checks at hand-over.** In the reference tree `make gate` passes in full, the
 end-to-end line included, so every given test has passed against some implementation. Area E's
@@ -96,7 +98,7 @@ enough. Most spec defects were found by writing test tables and exit lists, not
 
 1. `git log --oneline master..m3a`: twenty-two commits with the trailer.
 2. Copied files unchanged:
-   `for f in $(cd docs/plans/M3a/files && find . -type f ! -name Makefile-task21); do cmp "docs/plans/M3a/files/$f" "$f"; done`
+   `for f in $(cd docs/plans/M3a/files && find . -type f ! -name Makefile-task21 ! -name strict.rs-task01); do cmp "docs/plans/M3a/files/$f" "$f"; done`
 3. `git diff master..m3a --stat -- docs/design.md docs/specs docs/plans docs/runbook.md AGENTS.md CLAUDE.md deny.toml`
    is empty.
 4. `make gate`, `make audit`, `make verify-device`, `tools/check-m3a-device.sh`.

docs/plans/M3a/files/crates/proto/tests/strict.rs-task01

@@ -0,0 +1,128 @@
+//! Every JSON object in every fixture must reject an unknown key. Do not edit.
+//!
+//! The other test files check unknown fields in a few hand-picked places. This one checks all of
+//! them: it walks each fixture, adds one unknown key to one object at a time, at every depth, and
+//! requires that the result no longer decodes.
+
+use proto::{AuditRecord, Envelope, Grant, LogRecord};
+use serde::de::DeserializeOwned;
+use serde_json::Value;
+
+/// Every copy of `value` that has exactly one extra key in exactly one object.
+fn with_one_unknown_key(value: &Value) -> Vec<Value> {
+    let mut out = Vec::new();
+    match value {
+        Value::Object(map) => {
+            let mut extended = map.clone();
+            extended.insert("zz_unknown".to_string(), Value::Bool(true));
+            out.push(Value::Object(extended));
+            for (key, child) in map {
+                for changed in with_one_unknown_key(child) {
+                    let mut copy = map.clone();
+                    copy.insert(key.clone(), changed);
+                    out.push(Value::Object(copy));
+                }
+            }
+        }
+        Value::Array(items) => {
+            for (i, child) in items.iter().enumerate() {
+                for changed in with_one_unknown_key(child) {
+                    let mut copy = items.clone();
+                    copy[i] = changed;
+                    out.push(Value::Array(copy));
+                }
+            }
+        }
+        _ => {}
+    }
+    out
+}
+
+/// Returns how many variations were tried, so callers can check the walk reached nested objects.
+fn check<T: DeserializeOwned>(what: &str, text: &str) -> usize {
+    let value: Value = serde_json::from_str(text).unwrap_or_else(|e| panic!("{what}: {e}"));
+    assert!(
+        serde_json::from_value::<T>(value.clone()).is_ok(),
+        "{what}: fixture must decode"
+    );
+    let variations = with_one_unknown_key(&value);
+    for changed in &variations {
+        assert!(
+            serde_json::from_value::<T>(changed.clone()).is_err(),
+            "{what}: accepted an unknown key: {changed}"
+        );
+    }
+    variations.len()
+}
+
+fn fixture(path: &str) -> String {
+    let full = format!("{}/tests/fixtures/{path}", env!("CARGO_MANIFEST_DIR"));
+    std::fs::read_to_string(&full).unwrap_or_else(|e| panic!("{full}: {e}"))
+}
+
+#[test]
+fn envelopes_reject_unknown_keys_at_every_depth() {
+    for name in [
+        "tool_request.json",
+        "tool_response_pending.json",
+        "tool_response_result.json",
+        "tool_response_failed.json",
+        "tool_response_denied.json",
+        "error.json",
+        "turn.json",
+        "turn_event_tool_result.json",
+        "turn_event_content.json",
+        "turn_event_retrying.json",
+        "turn_done.json",
+        "error_session_full.json",
+    ] {
+        // Envelope, msg and body: three objects; turn_done also has a usage object.
+        let want = if name == "turn_done.json" { 4 } else { 3 };
+        assert_eq!(
+            check::<Envelope>(name, &fixture(&format!("wire/{name}"))),
+            want,
+            "{name}"
+        );
+    }
+}
+
+#[test]
+fn audit_records_reject_unknown_keys_at_every_depth() {
+    for (i, line) in fixture("records/audit.jsonl").lines().enumerate() {
+        // The record and its event: two objects. Decision and approval events also hold an
+        // outcome object.
+        let want = if line.contains("\"outcome\"") { 3 } else { 2 };
+        assert_eq!(
+            check::<AuditRecord>(&format!("audit.jsonl:{}", i + 1), line),
+            want
+        );
+    }
+}
+
+#[test]
+fn log_records_reject_unknown_keys_at_every_depth() {
+    let mut tried = 0;
+    for (i, line) in fixture("records/session.jsonl").lines().enumerate() {
+        tried += check::<LogRecord>(&format!("session.jsonl:{}", i + 1), line);
+    }
+    // Seven records, plus the one tool call inside the first assistant record.
+    assert_eq!(tried, 8);
+}
+
+#[test]
+fn usage_log_records_reject_unknown_keys_at_every_depth() {
+    let mut tried = 0;
+    for (i, line) in fixture("records/session_usage.jsonl").lines().enumerate() {
+        tried += check::<LogRecord>(&format!("session_usage.jsonl:{}", i + 1), line);
+    }
+    // Seven records, plus the one tool call inside the first assistant record.
+    assert_eq!(tried, 8);
+}
+
+#[test]
+fn grants_reject_unknown_keys_at_every_depth() {
+    let grant: Grant = toml::from_str(&fixture("grant/full.toml")).unwrap();
+    let text = serde_json::to_string(&grant).unwrap();
+    // The grant and its constraints: two objects.
+    assert_eq!(check::<Grant>("full.toml as JSON", &text), 2);
+}