docs(board): record ea2a378 with_jsonl_audit fix — EPIPHANIES E-AUDIT-1 + PR_ARC entry

Closes the board-hygiene gap: the May 26 signature fix (io::Result -> AuditError,
form 1 / W2's instinct) shipped touching only the .rs file; the board still
recorded only PR #366's introduction of the constructor. E-AUDIT-1 captures the
generalizable lesson (default-feature cargo check masks feature-gated E0277s;
error-type honesty over lossy From-coercion).

https://claude.ai/code/session_017gZ6sPRXYPj5n7uJ7NBtRv

Author: claude

.claude/board/EPIPHANIES.md

@@ -1,3 +1,17 @@
+## 2026-05-27 — E-AUDIT-1 — `with_jsonl_audit` jsonl-feature build break: a default-feature `cargo check` masks feature-gated error-type mismatches
+
+**Status:** FINDING
+
+**Click:** `UnifiedBridge::with_jsonl_audit` (added in PR #366 as the OQ-7-3 opt-in constructor, `#[cfg(feature = "jsonl")]`) was typed `-> std::io::Result<Self>`, but its body is `JsonlAuditSink::new(...)?` and `JsonlAuditSink::new -> Result<Self, AuditError>`. `AuditError` carries `Io(#[from] std::io::Error)` (the io→AuditError direction) but there is **no** reverse `From<AuditError> for std::io::Error`, so the `?` could not coerce `AuditError` into the declared `io::Error` return — E0277. The **default-feature `cargo check` skips this path entirely** (the constructor is feature-gated), so the break only surfaced when CI built `--features jsonl`.
+
+**Fix (commit `ea2a378`, branch `claude/activate-lance-graph-att-k2pHI`):** one line — return the honest error type `Result<Self, crate::audit_sink::AuditError>`. Two equivalent ~3-line forms existed: (1) change the return type to `Result<Self, AuditError>` [taken — "W2's instinct"]; (2) add a crate-wide `impl From<AuditError> for std::io::Error` and keep the `io::Result` signature. Form 1 chosen: the form-2 coercion would lossily flatten `ChannelFull` / `Serialize` / `SchemaMigration` / `Lance` / `Arrow` into `io::Error::other`, lying about the failure class for every future caller. Zero callers depended on the old signature (grep across all cloned repos: only the def + one doc-comment mention), so the signature change broke nothing. `cargo check/test -p lance-graph-callcenter --features jsonl` clean (137 tests).
+
+**Lesson (generalizes):** a `#[cfg(feature = …)]` fn whose body uses `?` across two error types is invisible to a default-feature `cargo check`. Any crate with optional-feature error paths needs a CI matrix that builds each feature (or `--all-features`), else these E0277s ship to whoever first enables the feature — here, the still-queued MedCare-rs sprint-2 item 5 that consumes this constructor. And: error-type honesty beats `From`-coercion convenience — return the real domain error rather than a lossy `into()` to a narrower std type.
+
+**Cross-ref:** PR #366 (constructor introduction, OQ-7-2/7-3 locks); `audit_sink/mod.rs::AuditError`; TD-SDR-AUDIT-PERSIST-1 in TECH_DEBT.md (the JSON-as-debt reframe — orthogonal to this signature fix).
+
+---
+
 ## 2026-05-16 — E-SIMD-SWEEP-1 — PR #398 was the 5th violation, not the first; the SIMD source-of-truth invariant is retroactive
 
 **Status:** FINDING

.claude/board/PR_ARC_INVENTORY.md

@@ -35,6 +35,18 @@
 
 ---
 
+## callcenter/audit-fix — fix(callcenter): `with_jsonl_audit` returns `Result<Self, AuditError>` (branch work)
+
+**Status:** On branch `claude/activate-lance-graph-att-k2pHI` (HEAD `ea2a378`, not yet a PR). 1-line `.rs` change + this board record (EPIPHANIES E-AUDIT-1, prepended 2026-05-27).
+
+- **Added** — nothing new; retypes `UnifiedBridge::with_jsonl_audit` return from `std::io::Result<Self>` → `Result<Self, crate::audit_sink::AuditError>` (`unified_bridge.rs:315`). Resolves an E0277 that only the `--features jsonl` build surfaced (the default `cargo check` skips the feature-gated path).
+- **Locked** — audit constructors return the **domain** error (`AuditError`), not `io::Result`. **No** crate-wide `From<AuditError> for std::io::Error` coercion (rejected: lossy across the non-`Io` variants `ChannelFull`/`Serialize`/`SchemaMigration`/`Lance`/`Arrow`). Optional-feature error paths must be CI-checked under their feature, not just default-feature (E-AUDIT-1).
+- **Deferred** — none. MedCare-rs sprint-2 item 5 (first real caller) consumes the `AuditError` signature directly; any caller needing `io::Result` interop adds a local `map_err`, not a crate-wide `From`.
+- **Docs** — EPIPHANIES E-AUDIT-1.
+- **Confidence (2026-05-27):** working — `cargo check/test -p lance-graph-callcenter --features jsonl` clean at commit time (137 tests); tree clean; zero callers depend on the old signature.
+
+---
+
 ## sprint-13/W-I1 — impl(sprint-13): D-CSV-13b i4 batch SIMD dispatch + tests (in PR)
 
 **Status:** In PR (branch `claude/sprint-13-w-i1-salvage`, HEAD `c9c1c79`, awaiting user merge). 4 commits on the branch: `cdc84ec` salvage W-I1 i4_eval::batch impl + criterion scaffold (recovered from cleaned worktree) → `a356e64` SIMD-vs-scalar parity tests + repr(u8) enum invariant (5 new randomised tests over 10 sizes, criterion 0.5 dev-dep, dead-code warning fix) → `d8d1437` AVX-512 dim-extract sign-extend fix (the bug that made the salvage path silently produce wrong bytes on negative thresholds) → `c9c1c79` `scalar_impl` made `#[doc(hidden)] pub` for bench access.