feat: finish mailbox evidence scanner mvp

docs/email-evidence-canon.md

@@ -36,6 +36,7 @@ coordination runtime decides whether those facts satisfy a coordination case.
 | `unsubscribe_or_opt_out` | `notification.channel.unsubscribe_received` | `fail.unsubscribed` |
 | `unknown_return_message` | `notification.endpoint.unknown` | `undef.conflicting_evidence` |
 | `challenge_response` | `interaction.unverified_actor_interaction` | `undef.identity_uncertain` |
+| `parse_failed` | `diagnostic.message.parse_failed` | `undef.parse_failed` |
 
 ## Overclaim Prevention
 
@@ -45,6 +46,7 @@ coordination runtime decides whether those facts satisfy a coordination case.
 - Out-of-office does not prove recipient awareness or action.
 - Human reply does not prove legal acceptance.
 - Unknown return messages remain visible.
+- Parse failures are diagnostic rows, not delivery or interaction outcomes.
 - Scanner and proxy interactions must stay below identity-bound interaction.
 
 ## Endpoint Quality Hints

docs/initial-runtime-architecture.md

@@ -74,10 +74,14 @@ Examples:
 - `complaint_or_abuse` -> `notification.channel.complaint_received`
 - `unsubscribe_or_opt_out` -> `notification.channel.unsubscribe_received`
 - `out_of_office` -> `interaction.out_of_office_received`
+- `challenge_response` -> `interaction.unverified_actor_interaction`
 - `human_reply` -> `interaction.reply_received`
+- `parse_failed` -> `diagnostic.message.parse_failed`
 
 The mapper does not emit evidence for unrelated messages. Unknown return
-messages stay visible as `notification.endpoint.unknown`.
+messages stay visible as `notification.endpoint.unknown`. Parse failures are
+visible as diagnostics without claiming delivery, interaction, identity, or
+endpoint quality.
 
 ## coordination-engine Alignment