docs(sp7): README — Per-Line Adjustment Audit section

README.md

@@ -154,6 +154,48 @@ parses and rejects claims, the inbox reflects the new
 | POST   | `/api/inbox/rejected/resubmit`                | `{claim_ids: [...]}`. `200` with `conflicts` for non-rejected.   |
 | GET    | `/api/inbox/export.csv?lane=<lane>`           | Streams CSV of the lane's rows.                                  |
 
+## Per-Line Adjustment Audit
+
+Every 835 CAS segment is tied back to the specific 837 service line it
+adjudicates, instead of being aggregated to the claim level. The match
+runs **eagerly** at 835 ingest time so the audit trail is stable across
+re-reads (a re-migration is required if the algorithm changes).
+
+### Where to find it
+
+- **ClaimDrawer → "Line Reconciliation" tab** — side-by-side view of the
+  837 SV1 lines and 835 SVC composites with per-line CAS reasons.
+- **ClaimDrawer → ServiceLinesTable** — every billed line now shows its
+  paid amount and adjustment sum on the right.
+- **RemitDrawer → CasAdjustmentsPanel** — each CAS row carries a
+  `proc · #N` reference; claim-level CAS clusters separately.
+- **ClaimDrawer → MatchedRemitCard** — a `lines: N/M matched` badge
+  lights up amber when at least one line is unmatched.
+
+### Match criteria (strict)
+
+A 835 SVC composite matches a 837 SV1 line iff all four criteria align:
+
+| Field         | Rule                                            |
+| ------------- | ----------------------------------------------- |
+| Procedure     | Exact match (case-insensitive, uppercased).     |
+| Modifiers     | Set-equal (order-independent).                  |
+| Service date  | Exact match (both null counts as a match).      |
+| Units         | Exact match (both null counts as a match).      |
+
+Unmatched lines surface as a **soft warning** — the claim still posts to
+PAID/PARTIAL/RECEIVED, but the Inbox shows the unmatched count and the
+drawer surfaces a per-line "no 837 line matched" note.
+
+### Line-level endpoints
+
+| Method | Path                                                | Notes                                                                                  |
+| ------ | --------------------------------------------------- | -------------------------------------------------------------------------------------- |
+| GET    | `/api/claims/{claim_id}/line-reconciliation`        | Dedicated view for the drawer tab.                                                     |
+| GET    | `/api/claims/{claim_id}`                            | Now includes a slim `lineReconciliation[]`.                                            |
+| GET    | `/api/remittances/{remittance_id}`                  | Now includes `serviceLinePayments[]` + `claimLevelAdjustments[]`.                      |
+| GET    | `/api/inbox/lanes`                                  | `matched_remittance` payload gains `matched_lines` + `total_lines`.                    |
+
 ### Scoring
 
 4-field weighted (sum = 100):