bxcore: sanitize::refuse, what a memory write may never hold

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

docs/implementer-log.md

@@ -6,6 +6,7 @@ reviewer adds findings under "Reviews" once per milestone.
 
 | Task | Date | Status | Gate runs | First gate | Deviations | Notes | Model |
 |---|---|---|---|---|---|---|---|
+| M5b/04-sanitize-refuse | 2026-09-26 | done | 1 | pass | none | Copied the given files from `docs/plans/M5b/files/`: the skeleton `bxcore/src/sanitize/refuse.rs` and the tests `bxcore/tests/sanitize_refuse.rs`, `bxcore/tests/sanitize_refuse_corpus.rs`, `bxcore/tests/support/keys.rs`. `bxcore/src/sanitize/mod.rs`: replaced the whole file (E1), adding `mod refuse;` and `pub use refuse::{Refusal, refuse};`. `bxcore/src/sanitize/tags.rs`: `next_tag` became `pub(super)` (E2), nothing else changed. Filled the eight functions in `refuse.rs` in the given order, each from its comment: `control` (`c.is_control() && c != '\n' && c != '\t'`), `first_char` (`char_indices().find` the first char the rule accepts, `map` to its byte offset), `private_use` (`u32::from(c)` inside one inclusive `PRIVATE_USE` range, as `invisible` does for `DEFAULT_IGNORABLE`), `noncharacter` (`0xFDD0..=0xFDEF` or `code & 0xFFFE == 0xFFFE`), `listed_tag` (`next_tag(text)` mapped to `before.len()`), `starts_word` (`!before.chars().next_back().is_some_and(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')`), `key_run` (`take_while` the run, counting chars and noting an upper and a digit, length in range and, if `mixed`, both seen), `private_key` (`match_indices("-----BEGIN")`, the line before trims empty and the BEGIN line trim_end()s onto one of `PRIVATE_KEY_ENDS`). Step 2 showed the three named E0432; step 3 compiled with the unfilled-function dead-code warnings. `key_run` failed once on `RangeInclusive` precedence: `secret.min..=secret.max.contains(&count)` parsed as a range, fixed by `(secret.min..=secret.max).contains(&count)`. After the edits `cargo check -p bxcore` is clean; `sanitize_refuse` 14 passed, `sanitize_refuse_corpus` 2 passed, `sanitize_tags` 15, `sanitize_corpus` 3. `cargo fmt --all`; `make gate` printed `gate: ok`; `cargo test --workspace` reports 996 passed, plus the gate's separate loopd `end_to_end` ignored test, for 997 total. No new dependency, so `Cargo.lock` is unchanged. | ornith-1.5-35b-a3b |
 | M5b/03-sanitize-tags | 2026-09-26 | done | 1 | pass | none | Copy of the skeleton `bxcore/src/sanitize/tags.rs` and the three tests `bxcore/tests/sanitize_tags.rs`, `bxcore/tests/sanitize_corpus.rs`, `bxcore/tests/support/tags.rs`. Created `bxcore/src/sanitize/mod.rs` (E1); added `pub mod sanitize;` to `bxcore/src/lib.rs` between `pub mod memory;` and the `#[cfg(feature = "secrets")]` line (E2). Filled `push_escaped` (walk `tag.text.chars()`, write the first bracket as `&lt;` and the second as `&gt;`, push every other character as itself). Filled `next_tag` (iterate `text.match_indices('<')`, `split_at_checked` the offset, `TAGS.iter().find` the tag the rest starts with, return the text before, the tag, and the text after; otherwise fall through to `None`). Step 2 showed the two named E0432; step 3 compiled with the two `todo!()`s, 3 pass and 12 fail in `sanitize_tags`, 3 fail in `sanitize_corpus`, every failure `not yet implemented`. My first `next_tag` returned `None` on the first `<` that did not start a tag, so `attack_texts_come_back_neutralised` and `the_forged_turns_come_back_exactly_so` each left a tag (the failure named it); changed the `find` to `if let Some` so the loop continues, matching the comment's "After the loop, None". After the edits the step-3 command shows 15 passed in `sanitize_tags` and 3 passed in `sanitize_corpus`; `cargo check -p bxcore` is clean. `cargo fmt --all`; `make gate` printed `gate: ok`; `cargo test --workspace` reports 980 passed, plus the gate's separate loopd `end_to_end` ignored test, for 981 total. No new dependency, so `Cargo.lock` is unchanged. | ornith-1.5-35b-a3b |
 | M5b/02-secrets-move | 2026-09-26 | done | 1 | pass | none | Copied the given files from `docs/plans/M5b/files/`: `bxcore/src/secrets.rs`, `bxcore/tests/{secrets,secrets_race}.rs`, `bxcore/tests/support/tmp.rs`, `loopd/tests/no_secrets.rs`, and new versions of `gatewayd/tests/{config,mm_edit,mm_rest}.rs` and `support/gateway.rs` (only an import changes in each). `bxcore/Cargo.toml`: `zeroize` becomes optional, `[features] secrets = ["dep:zeroize"]`, and two `[[test]]` entries with `required-features = ["secrets"]` so the two files run only when the feature is on; `bxcore/src/lib.rs` doc comment renamed, and `#[cfg(feature = "secrets")] pub mod secrets;` inserted between `memory` and `sha1`. `gatewayd/Cargo.toml`: `bxcore` gains `features = ["secrets"]` and its own `zeroize` dependency is dropped; `gatewayd/src/lib.rs` loses `pub mod secrets`. `gatewayd/src/config.rs` imports `SecretSpec`/`SecretSource` from `bxcore` and drops the two types plus `impl SecretSpec::source` (still called through the import via `problem` and `token_source`). `gatewayd/src/main.rs` imports `bxcore::secrets`, passes `"gatewayd"` as `role` to `load`, and uses the `let env = |k: &str| std::env::var_os(k);` closure; `gatewayd/src/mm/rest.rs` and `serve/mod.rs` import `Secret` from `bxcore`. `git rm`'d `gatewayd/src/secrets.rs` and its two secret tests. `docs/dependencies.md` lists `zeroize` under `bxcore`, feature `secrets` (enabled by gatewayd, never by loopd). Step 2 showed exactly the named E0432 failures and the two named `no_secrets` failures; after the edits `cargo test -p bxcore --features secrets` (11 in `secrets`, 5 in `secrets_race`), `cargo test -p bxcore` skips them, all four `no_secrets` pass, and `cargo test -p gatewayd` passes including `main`. Step 7 greps/trees as expected (no `zeroize`/`crate::secrets`/`gatewayd::secrets` in gatewayd, `loopd` does not enable the feature, `gatewayd` does, `loopd` builds alone, only `no_secrets.rs` untracked, nothing changed in the other crates). `cargo fmt --all`; `make gate` printed `gate: ok` with 963 tests (956 before; the 13 gatewayd secret tests moved into bxcore, plus 3 new in `bxcore/tests/secrets.rs` and 4 new in `loopd/tests/no_secrets.rs`, +7 net). `zeroize` moved from gatewayd to bxcore, so `Cargo.lock` changed. | ornith-1.5-35b-a3b |
 | M5b/01-invalid-arguments-detail | 2026-09-26 | done | 1 | pass | none | Copied the 13 given files from `docs/plans/M5b/files/` (two new: `bxcore/tests/fixtures/wire/tool_response_denied_detail.json` and `brokerd/tests/invalid_detail.rs`; new versions of `bxcore/tests/wire.rs` and `strict.rs`; new versions of `brokerd/tests/{admin,broker,broker_pending,courier,ledger,serve}.rs` where `broker.rs`/`serve.rs` are the `-task01` files; new versions of `loopd/tests/{broker_port,tools,turn_broker}.rs`); step 2 showed exactly the named failures (`strict::envelopes_reject_unknown_keys_at_every_depth` on the new fixture, two `E0559` in `wire`, and ten non-compiling brokerd/loopd test targets with the named error kinds). Made all the edits exactly as the task gives: `bxcore/src/wire.rs` `ToolResponse::Denied` gains `detail: Option<String>` with the skip/serde attributes; `brokerd/src/args.rs` adds `MAX_DETAIL=300` and `ArgsError::detail` (control chars and U+2028/U+2029 -> space, cut to 300 chars); `brokerd/src/policy/mod.rs` `Denial` gains `detail`, `Denial::new` sets `None`, `decide` sets it for `InvalidArguments` only, the two `DeniedByGrant` arms set `None`; `brokerd/src/ledger/mod.rs` `Decided::Denied` now holds a `Denial` (every arm rebuilt through `Denial::new` except the `RecordPayload::Denial` arm which passes the `Denial` through); `brokerd/src/broker.rs` `handle` sends the denial's detail, the two `pending` arms send `None`; `loopd/src/tools.rs` adds `denial_message(reason, detail)` before `FakeTools` and `FakeTools::call` sends `detail: None`; `loopd/src/turn.rs` imports `denial_message` and reads `detail` into it, the `TurnEvent::ToolDenied` event keeping only the reason. Did not touch `gatewayd`, `bxctl` or `bxcore/src/audit.rs`. `cargo fmt --all`; `cargo test -p bxcore -p brokerd -p loopd` every suite passes (including the eight `invalid_detail` tests); step 6 `grep -rn "Decided::Denied(DenyReason"` prints nothing and `git diff --stat -- crates/gatewayd crates/bxctl crates/bxcore/src/audit.rs` prints nothing; `cargo test --workspace` reports 955 passed and the gate's separate loopd `end_to_end` ignored test adds 1, for 956 total. No new dependency, so `Cargo.lock` is unchanged. | ornith-1.5-35b-a3b |