Iter 8. Lands the lifecycle half of ADR-120 §2.5: a bounded, in-place,
no_std-compatible ring of IdentityEmbeddings. Insertion is O(1); when
full, push evicts the oldest entry, whose Drop runs and zeroizes the
f32 storage. drain() clears the ring on the coherence-gate Recalibrate
action (ADR-121 §2.4).
Added:
- src/embedding_ring.rs (no_std-compatible; no heap):
* EmbeddingRing struct with [Option<IdentityEmbedding>; RING_CAPACITY=64]
backing array, head cursor, count
* EmbeddingRing::new() / Default impl
* push(emb) -> Option<IdentityEmbedding> (evicted oldest when full)
* len / is_empty / capacity / is_full / iter
* iter() returns occupied slots in insertion order (oldest first)
* drain() -> usize (empties the ring, returns count drained)
- pub use EmbeddingRing, RING_CAPACITY from lib.rs
Uses `[const { None }; RING_CAPACITY]` (stable since 1.79) to initialize
the slot array for a non-Copy element type.
tests/embedding_ring.rs (9 named tests, all green):
new_ring_is_empty
default_constructor_matches_new
push_below_capacity_returns_none
iter_yields_in_insertion_order
push_at_capacity_evicts_oldest_and_returns_it
(verifies eviction reports the FIRST pushed value, not the last)
push_beyond_capacity_keeps_last_n_entries
(after 74 pushes into a 64-slot ring, the surviving 64 are positions 10..74)
drain_empties_the_ring_and_returns_count
drain_on_empty_ring_returns_zero
ring_can_be_refilled_after_drain
(post-drain push lands cleanly at index 0; iter yields exactly that entry)
ACs progressed:
- I2 ↑ — ring eviction and explicit drain both drop IdentityEmbeddings,
which the iter-7 Drop impl zeroizes. The "in-RAM-only" lifecycle is now
end-to-end: bounded buffer in, FIFO out, drain on Recalibrate.
Test config:
- cargo test --no-default-features → 31 passed (22 + 9)
- cargo test → 53 passed (44 + 9)
Out of scope (next iter target):
- PrivacyGate::demote(frame, target_class) — ADR-120 §2.4 monotonic class
transition with field zeroization, refusing demote-to-Raw (compile-fail).
- SoulMatchOracle stub trait + no-op default impl (ADR-121 §2.6) so the
Recalibrate exemption hook is wireable from `--features soul-signature`.
Co-Authored-By: claude-flow <ruv@ruv.net>
60eaaa5af1