Advance forge rollout, Ethereum rails, and NBC sources

evolution/proposals/ECP-0090-pat-derived-broadcast-identity.md

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+# ECP-0090: PAT-Derived Broadcast Identity Promotion
+
+Status: Implemented
+
+## Decision
+
+Extend default discovery identity synthesis to probe early MPEG-TS packets for Program Association Table (PAT) data and use that to strengthen broadcast-scoped stream IDs.
+
+Current rule:
+
+- If source/channel metadata already yields a usable broadcast identity, use it.
+- If transport probing finds PAT data, fill missing `transport_stream_id` and `program_number`.
+- If PAT shows exactly one non-zero program, that program is eligible for broadcast-scoped convergence.
+- If PAT is ambiguous (multiple non-zero programs), do not guess; keep `program_number` unset and fall back to source scope when needed.
+- If the probe sees ATSC PSIP traffic, label the standard as `atsc`; otherwise use a generic `mpegts` fallback when PAT is the only signal.
+
+## Motivation
+
+ECP-0089 fixed the first duplication bug by preferring channel metadata over source-local IDs. That still left a hole:
+
+- raw TS sources without lineup metadata could not converge,
+- channel metadata could be incomplete or inconsistent,
+- and weak identity inputs risked accidental convergence on the wrong broadcast.
+
+PAT-derived identity gives us a stronger on-wire fingerprint without waiting for full PSIP/VCT parsing.
+
+## Scope
+
+In scope:
+
+- PAT parsing in `ec-ts`
+- bounded transport probing for `tsid` / single-program extraction
+- source integration for raw TS inputs and HDHomeRun enrichment
+- tests that enforce "single program promotes, ambiguous stream does not"
+
+Out of scope:
+
+- full ATSC VCT/MGT descriptor parsing
+- DVB service table parsing
+- cryptographic origin authentication for discovery announcements
+
+## Alternatives considered
+
+- Keep trusting channel metadata only. Rejected because it leaves raw TS paths weak and incomplete.
+- Always promote from PAT even with multiple programs. Rejected because it guesses the channel and increases junk-collision risk.
+- Require manual `--stream-id` for TS inputs. Rejected because it pushes canonicalization burden onto operators.
+
+## Rollout / Reversibility
+
+- Additive and reversible: explicit `--stream-id` still overrides everything.
+- Roll back by removing PAT probing and returning to metadata-only promotion.
+- Future PSIP/VCT work can refine the broadcast identity without changing the override surface.