Found by the manager_routing fuzz target (docs/research/fuzzing.md \u00a77.8):
- ChannelManager::open_channel / adopt_channel used
HashMap::insert(...).is_some() as a collision check \u2014 insert REPLACES
the existing entry, so a duplicate adopt/open installed the new state,
dropped the live channel's demux_sender (spurious EOF to its readers,
subsequently routed chunks lost) and still returned
Err(ChannelExists). Fixed with contains_key pre-check; map untouched
on collision. Regression tests: adopt_channel_duplicate_id_leaves_
live_channel_intact, open_channel_duplicate_id_leaves_live_channel_
intact.
New fuzz targets (\u00a77.4 step 3):
- manager_routing: Arbitrary op sequences over ChannelManager; exact
counter models (parked/dropped must equal the manager's monotonic
counters), parked-bytes bound per \u00a76.2-1, clear_all ledger-vs-map
semantics, drainer-byte reconciliation (lossless routing)
- envelope_semantic: constructors -> serde -> write_frame/read_frame
structural round-trip; event-type constants; call.error parse-back
- spec_parse: OpRegisterRequest::from_json -> rebuild -> registry
registration (attacker schemas compile at register, CF-003)
- fuzz/shared/src/arbitrary_value.rs: bounded Arbitrary for
serde_json::Value; 20 spec_parse + 4 manager_routing seeds
- corpus replay for the new targets in fuzz/shared tests
Verification: cargo test 684 passed (682 + 2 regression); clippy
-D warnings clean (main + fuzz/shared); fmt clean (main + fuzz);
cargo fuzz build clean; 20 s smoke on all three new targets clean
(manager_routing 79k, envelope_semantic 141k, spec_parse 517k runs);
crash input replays clean post-fix
- fuzz/ workspace (nightly-pinned via rust-toolchain.toml, excluded from
the main workspace and the published package): chunk_header and
envelope_frame targets per fuzzing.md \u00a77.1
- invariant logic in fuzz/shared (stable-toolchain crate): committed
corpus replay as plain cargo test (quinn CI pattern, \u00a77.2 tier 3)
- envelope target adds FrameError shape-partition asserts, exact
consumption accounting, structural write_frame round-trip, serde
key-contract, and a trailing-byte probe (prefix counts body only)
- chunk_header target adds round-trip identity, TooLarge/short error
shape, is_eof, 8-byte consumption, input-never-mutated
- committed seed corpora: 245 deterministic seeds via
fuzz/gen_fuzz_seeds.py (truncations, len=0/MAX+1/u32::MAX, channel 0,
invalid UTF-8, deep nesting); grown corpora + artifacts gitignored
- fuzz/run-detached.sh: \u00a77.6 detached runner (setsid+nohup+log, fork
mode, rss/malloc limits) \u2014 campaigns never share fate with a session
- fuzz/json.dict; README; research doc \u00a77.7 records step-1 status
Verification: cargo fuzz build clean; stable side green (cargo test 682
passed, clippy -D warnings, fmt --check incl. fuzz/shared); corpus
replay 245 seeds green; detached 10-min campaigns on both targets
completed with zero crashes/OOMs/timeouts
glm-5.3-flash