feat: enhance mode routing with track_progress and context preservation (#506)

* feat: enhance mode routing with track_progress and context preservation

This PR implements enhanced mode routing to address two critical v1 migration issues:
1. Lost GitHub context when using custom prompts in tag mode
2. Missing tracking comments for automatic PR reviews

Changes:
- Add track_progress input to force tag mode with tracking comments for PR/issue events
- Support custom prompt injection in tag mode via <custom_instructions> section
- Inject GitHub context as environment variables in agent mode
- Validate track_progress usage (only allowed for PR/issue events)
- Comprehensive test coverage for new routing logic

Event Routing:
- Comment events: Default to tag mode, switch to agent with explicit prompt
- PR/Issue events: Default to agent mode, switch to tag mode with track_progress
- Custom prompts can now be used in tag mode without losing context

This ensures backward compatibility while solving context preservation and tracking visibility issues reported in discussions #490 and #491.

* formatting

* fix: address review comments

- Simplify track_progress description to be more general
- Move import to top of types.ts file

* revert: keep detailed track_progress description

The original description provides clarity about which specific event actions are supported.

* fix: add GitHub CI MCP tools to tag mode allowed list

Claude was trying to use CI status tools but they weren't in the
allowed list for tag mode, causing permission errors. This fix adds
the CI tools so Claude can check workflow status when reviewing PRs.

* fix: provide explicit git base branch reference to prevent PR review errors

- Tell Claude to use 'origin/{baseBranch}' instead of assuming 'main'
- Add explicit instructions for git diff/log commands with correct base branch
- Fixes 'fatal: ambiguous argument main..HEAD' error in fork environments
- Claude was autonomously running git diff main..HEAD when reviewing PRs

* fix prompt generation

* ci pass

---------

Co-authored-by: Ashwin Bhat <ashwin@anthropic.com>

action.yml

@@ -73,6 +73,10 @@ inputs:
     description: "Enable commit signing using GitHub's commit signature verification. When false, Claude uses standard git commands"
     required: false
     default: "false"
+  track_progress:
+    description: "Force tag mode with tracking comments for pull_request and issue events. Only applicable to pull_request (opened, synchronize, ready_for_review, reopened) and issue (opened, edited, labeled, assigned) events."
+    required: false
+    default: "false"
   experimental_allowed_domains:
     description: "Restrict network access to these domains only (newline-separated). If not set, no restrictions are applied. Provider domains are auto-detected."
     required: false
@@ -140,6 +144,7 @@ runs:
         USE_STICKY_COMMENT: ${{ inputs.use_sticky_comment }}
         DEFAULT_WORKFLOW_TOKEN: ${{ github.token }}
         USE_COMMIT_SIGNING: ${{ inputs.use_commit_signing }}
+        TRACK_PROGRESS: ${{ inputs.track_progress }}
         ADDITIONAL_PERMISSIONS: ${{ inputs.additional_permissions }}
         CLAUDE_ARGS: ${{ inputs.claude_args }}
         ALL_INPUTS: ${{ toJson(inputs) }}
@@ -247,6 +252,7 @@ runs:
         PREPARE_ERROR: ${{ steps.prepare.outputs.prepare_error || '' }}
         USE_STICKY_COMMENT: ${{ inputs.use_sticky_comment }}
         USE_COMMIT_SIGNING: ${{ inputs.use_commit_signing }}
+        TRACK_PROGRESS: ${{ inputs.track_progress }}
 
     - name: Display Claude Code Report
       if: steps.prepare.outputs.contains_trigger == 'true' && steps.claude-code.outputs.execution_file != ''