[samgbafa]

Behavior

• Limit raw combine inputs to at most twice the validated current member count. Duplicates count toward the limit.
• Return CombineError::TooManyShares without a member before request/share bindings, supplied-entry processing or algebra when the input exceeds the limit.
• Preserve binding-first verification, per-member deduplication and lowest-threshold-index selection within the limit.
• Add boundary, precedence and canonical identity-c3 mutation regressions. Identity decoding roles are unchanged; the specified mutated response returns the existing member-specific Invalid result.
• Append the exact bound and precedence to SPEC/README. No layout, algorithm, dependency, fixture, checker or node-runtime changes.

Base: 00643ae8b445e019b45a03923caf65400102825d
Head: bb6133098d247bd2c3fb67e3cfd3de6faee8096b

Verification

Executed on the final Rust source before the documentation-only additions:

• Tests first: one cargo test --locked -p tinycloud-threshold p3_ -- --nocapture run produced 3 passes and 2 behavior failures: over-limit acceptance and count-check precedence. The identity-c3 regression already passed before the guard.
• cargo test --locked -p tinycloud-threshold — 50 passed, 0 failed, 0 ignored; 0 doc-tests. Includes the existing primitive byte-for-byte comparison.
• cargo clippy --locked -p tinycloud-threshold --all-targets -- -D warnings — exit 0.
• cargo fmt --check -p tinycloud-threshold — exit 0.
• One native binary compiled the actual production modules with a local 4-member fixture: 8 inputs combine/decrypt/unwrap successfully; 9 return TooManyShares before binding/equation checks; 8 copies from one member return NotEnoughShares; bounded inputs retain all-bindings-before-algebra ordering; the canonical identity-c3 mutation returns Invalid for its issuing member. Compile and execution both exit 0. S0.1 has no public key-set constructor; the fixture is local to the temporary module harness, not a new product API.

All local Cargo work used isolated homes/target and two build jobs. Both granted slots were released immediately. The existing threshold lane in .github/workflows/rust.yml runs the full crate suite, including these inline tests; no CI configuration change is needed.

Dependency licences (unchanged)

Role	Dependency	Licence
Production	blst 0.3.16	Apache-2.0
Production	sha2 0.10.9	MIT OR Apache-2.0
Production	zeroize 1.8.2	Apache-2.0 OR MIT
Production	subtle 2.6.1	BSD-3-Clause
Production	rand_core 0.6.4	MIT OR Apache-2.0
Production	thiserror 2.0.18	MIT OR Apache-2.0
Development	proptest 1.9.0	MIT OR Apache-2.0
Development	rand_chacha 0.3.1	MIT OR Apache-2.0
Development	serde 1.0.228	MIT OR Apache-2.0
Development	serde_json 1.0.149	MIT OR Apache-2.0
Development	hex 0.4.3	MIT OR Apache-2.0

The crate retains the workspace TinyCloud EGPL v1.5 licence file, publish = false, existing release configuration and unwired workspace membership.

PROVENANCE

• TinyCloud's existing SPEC §3.6 and own input-bound policy: count limit, error precedence and unchanged accepted-length ordering.
• Existing TinyCloud derive.rs, error.rs and deterministic checkpoint.rs fixture/dealer: existing API conventions, valid responses and regression construction.
• Existing crate README and locked build metadata: unchanged dependency/licence inventory. Compiler-generated dependency-path metadata selected the matching prebuilt RNG artefacts for the temporary smoke; no dependency implementation was inspected.
• Existing threshold workflow: confirmation that all inline crate tests run in CI.
• No external implementation, new dependency implementation source or independent checker source was consulted for this change. Primitive JSON remains unchanged; the Rust-free count/error/precedence contract was sent to the separate checker owner without assigning checker edits.

Clean-room statement. tinycloud-threshold is written from published papers and standards only: Shamir 1979; Feldman 1987; Pedersen 1991; Gennaro–Jarecki–Krawczyk–Rabin 1999/2007; Boneh–Franklin 2001/2003; Fujisaki–Okamoto 1999; Desmedt–Jajodia 1997; Wong–Wang–Wing 2002; Herzberg–Jarecki–Krawczyk–Yung 1995; CHURP (ePrint 2019/017); vetKeys (ePrint 2023/616); RFC 9380; RFC 9180; the IRTF pairing-friendly-curves draft; and TinyCloud's own design and plan. No source code, tests, issues or other material from TACo, nucypher, nucypher-core, ferveo, umbral or taco-web (GPL-3.0/AGPL-3.0) was opened, fetched, cloned, searched or used. Dependencies are permissively licensed and listed in the PR. Each PR keeps a provenance log of the sources consulted.

test-ruling: TC-2219

The boundary and canonical identity-c3 regression additions are authorized by the owner disposition in TC-2219 comment ab185d99-1b8f-4cab-83a2-e235e0994ba1 and the scoped implementation instruction. Existing test assertions and fixtures are unchanged.

Details: TC-2219