feat: harden OpenSpec agent resilience

openspec/schemas/wealth-ledger-sdd/templates/spec.md

@@ -1,11 +1,17 @@
-## Purpose
-<!-- New capabilities only: one or two sentences (50+ characters) on what this capability is for. Delete this section for an existing capability. -->
+<!--
+Choose only the sections this delta needs; delete this guide before approval.
 
-## ADDED Requirements
+New capability only: add `## Purpose` with 1–2 sentences (50+ characters).
+Existing capability: do not add Purpose.
 
-### Requirement: <!-- requirement name -->
-<!-- requirement text -->
+Supported operations:
+- `## ADDED Requirements`: new complete Requirement blocks.
+- `## MODIFIED Requirements`: full existing Requirement blocks with every
+  surviving Scenario, then edited behavior.
+- `## REMOVED Requirements`: Requirement heading plus **Reason** and **Migration**.
+- `## RENAMED Requirements`: `FROM:` and `TO:` heading pairs only.
 
-#### Scenario: <!-- scenario name -->
-- **WHEN** <!-- condition -->
-- **THEN** <!-- expected outcome -->
+Every Requirement uses `### Requirement: <name>`, SHALL/MUST, and at least one
+`#### Scenario: <name>` with `- **WHEN**` and `- **THEN**`.
+Do not leave empty operation sections.
+-->