yoi/.yoi/tickets/00001KTFFY8E8/resolution.md

Implemented typed Ticket thread event logging for workflow audit events.

Changes:

• Added event kinds:
  • state_changed
  • intake_summary
• Preserved existing event kinds and historical compatibility.
• Added typed backend data/API:
  • TicketStateChange
  • TicketIntakeSummary
  • TicketBackend::add_state_changed(...)
  • TicketBackend::add_intake_summary(...)
  • TicketBackend::set_state_field(...) as a frontmatter-field update plus state_changed event helper for the next workflow-state slice.
• Parser now understands quoted event attributes and exposes typed metadata such as from, to, reason, state_field, and full attributes.
• Doctor validates required fields for state_changed and intake_summary where practical.
• TicketShow tool output includes new event metadata fields/attributes.
• Thread event append now prevalidates and prerenders metadata before opening/appending thread.md, preventing failed appends from corrupting the log.
• Create event author validation happens before writing a ticket record.
• Documentation now describes thread.md as append-only audit history, not current-state authority.

Validation after merge:

• cargo test -p ticket thread
• cargo test -p ticket
• cargo test -p yoi ticket
• cargo test -p pod ticket --lib
• cargo check --workspace --all-targets
• cargo fmt --check
• git diff --check HEAD~1..HEAD
• cargo build -p yoi
• target/debug/yoi ticket doctor
• nix build .#yoi --no-link --print-out-paths

External review approved after fixing prevalidation/partial-append safety.

explicit-ticket-workflow-state can proceed next.