Self assign the issue once we create the Pull request

[Satendra-SR]

On creating the pull request, I would like to self assign the targeted issue. Also, i don't want to remove anyone who is already assigned, Just self assign and keep anyone else as well under assignee if already have

[Satendra-SR]

Plan Version: v1
Status: Draft
Last Updated By: implementation-planner

Objective

Implement issue self-assignment when a PR is created, without removing any existing issue assignees.

Scope

• Add a rule-driven capability to append the PR author as an assignee on the target issue.
• Keep existing assignees unchanged.
• Trigger this behavior for PR creation flow (pull_request opened) via config.

Out of Scope

• Replacing or removing assignees.
• Backfilling assignees for old PRs/issues.
• Changing unrelated automation behavior (status transitions, labels, audit format).

Context

• Requested outcome: On PR creation, self-assign the targeted issue while preserving any existing assignees.
• Current behavior summary: The action parses Targets, resolves the issue, applies labels/status/audit comments, but does not assign users to the issue today.

Plan

1. Extend rules/config model with a new do directive for issue self-assignment from PR author (boolean flag).
2. Update action plan builder to map that directive into executable plan state.
3. Add issue API helper to append assignee(s) using issues.addAssignees and keep operation idempotent (skip if already assigned).
4. Wire main workflow (src/index.ts) to call the helper when the new plan flag is enabled, using pull_request.user.login as assignee.
5. Ensure failure policy is explicit: assignment errors that indicate non-assignable users should be logged and not silently remove assignees; decide whether to continue or fail based on existing error-handling conventions.
6. Add/adjust tests for rule parsing and assignment behavior (already-assigned, empty-assignee, API-call path).
7. Update docs/examples to show how to enable this on PR creation (opened) and clarify that existing assignees are preserved.

Files Expected To Change

• src/config.ts: add new rule directive type.
• src/rules/types.ts: add new ActionPlan field for assignment action.
• src/rules/router.ts: map new directive into plan.
• src/github/issue.ts: add helper for additive assignee assignment.
• src/index.ts: invoke assignment helper when rule is active.
• tests/* (new or existing): coverage for router + assignment path.
• README.md: document new rule behavior and semantics.
• examples/coloredcow-admin-sneha/.github/automation.yml: show opened-event usage for self-assignment.

Risks

• Assignee not assignable (permission/membership constraints): 422 from GitHub API.
  • Mitigation: handle this case explicitly with warning and deterministic behavior; do not affect existing assignees.
• Rule accidentally runs on non-create events: repeated API calls on synchronize.
  • Mitigation: document and exemplify opened-only rule; keep helper idempotent.
• Behavior regression in rule routing: new directive could break existing parsing.
  • Mitigation: add focused router tests and keep backward compatibility for existing directives.

Validation

• npm test
  • Expected: all tests pass, including new assignment/routing tests.
• npm run build
  • Expected: TypeScript compile succeeds with new rule types and call sites.
• npm run bundle (if source behavior changes for release artifacts)
  • Expected: dist/index.js updates without build errors.

Ready for Execution

• New rule directive is defined and parsed without breaking existing config.
• PR author is added to issue assignees additively (no removals).
• Behavior is configurable and shown for pull_request/opened.
• Tests cover success + idempotent/already-assigned + API error path.
• Build/test/bundle checks pass.

Assumptions To Preserve

• “Self assign” means assigning the PR author (pull_request.user.login) to the target issue.
• Existing assignees must remain untouched.
• Assignment feature is opt-in through rules configuration.

[Satendra-SR]

Execution Update

• Plan version used: v1
• Implementation status: completed
• Branch: codex/1-issue-self-assignment
• PR: feat: add additive issue self-assignment on PR open #2

Commands run and outcomes

• npm test: pass
• npm run build: pass
• npm run bundle: pass

Scope delivered

• added opt-in assign_issue_to_pr_author rule directive
• mapped directive through router/action plan
• implemented additive issue assignment via issues.addAssignees with idempotency and graceful handling for non-assignable users (422)
• wired runtime assignment from PR author login on configured events
• added test coverage for routing and assignment behavior
• updated docs and example config

Notes

• Execution proceeded on explicit local operator approval (yes) even though plan comment status remained Draft.