Title#

feat: release strategy design — multi-repo coordinated releases with staged E2E validation

Problem#

AgentSDE orchestrates individual issues in a single repo. There is no mechanism to group issues across repos into a coordinated release with shared RC branches, validation gates, and atomic promotion to master.

Task / Link#

Closes #343

Changes#

• plan/release-strategy.md — full design: lifecycle model, multi-repo coordination, data models, pipeline extensions, validation/gating model, API/webhook changes
• plan/release-manifest-schema.json — JSON Schema (draft-07) for the ReleaseManifest data model including ReleaseIssue, CrossRepoDependency, and E2EGateConfig sub-schemas
• plan/execution-plan.md — 15 ordered implementation tasks across 4 milestones (M1: data model, M2: single-repo RC flow, M3: multi-repo coordination, M4: E2E validation gates) with S/M/L complexity estimates and parallelisation opportunities

Notes#

• No code changes in this PR — design document only per issue acceptance criteria
• Open questions documented in release-strategy.md: DB entity vs. metadata grouping, minimum E2E tier set
• Sprint-aware planning explicitly deferred to a follow-on design

Testing#

Documentation-only PR — no TS/JS modified. Lint and test steps skipped per AGENTS.md §10.