Separate chat transcript ownership from runtime user

[chubes4]

Summary

• Add isolated transcript owner fields and migration/backfill behavior for existing chat sessions.
• Separate chat runtime user resolution from transcript owner resolution.
• Reject broad public-audience transcript ownership so public access cannot expose shared or agent-owner sessions.

Dependency

• Depends on Agents API principal-owned conversation-session contract: Add principal-owned conversation sessions Automattic/agents-api#175
• Tracks Separate chat transcript ownership from runtime execution user #2023.

Testing

• php tests/chat-transcript-owner-smoke.php
• php tests/agents-api-transcript-store-smoke.php
• composer lint -- --standard=phpcs.xml.dist <focused files>
• git diff --check
• php -l on touched PHP files

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Drafting the implementation, migration/test coverage, and PR description; Chris remains responsible for review and validation.

[homeboy-ci]

Homeboy Results — data-machine

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine --changed-since a0e623c

Test

✅ test — passed

• 790 passed

ℹ️ Auto-fix lint issues: homeboy refactor data-machine --from lint --write
ℹ️ Collect coverage: homeboy test data-machine --coverage
ℹ️ Save test baseline: homeboy test data-machine --baseline
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine --changed-since a0e623c

Audit

✅ audit — passed

• requested_detectors — 180 finding(s)
• dead_code — 56 finding(s)
• test_coverage — 36 finding(s)
• intra-method-duplication — 9 finding(s)
• parallel-implementation — 7 finding(s)
• dead_guard — 2 finding(s)
• Chat — 1 finding(s)
• Directives — 1 finding(s)
• Retention — 1 finding(s)
• structural — 1 finding(s)
• Total: 294 finding(s)

Deep dive: homeboy audit data-machine --changed-since a0e623c

Tooling versions

• Homeboy CLI: homeboy 0.182.0+2eff62f3
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 25a2f3e
• Action: unknown@unknown