[#33]: handle Codex v0.129.0 sessionId relocation to Thread object

[delexw]

Fixes #33

Summary

Codex v0.129.0 (2026-05-07) restructured where session identity is surfaced:

• PR #20437 added a session_id field to session data alongside the existing id field.
• PR #21336 moved sessionId from a top-level position onto the Thread sub-object in the v2 API.

codex-trace was reading the session identifier exclusively from payload.id in session_meta entries. Sessions written by v0.129.0+ that omit id in favour of the new fields would produce an empty session identifier, silently breaking session correlation and grouping.

Changes

src-tauri/src/parser/entry.rs

• Added extract_session_id(payload) — a shared helper that probes three paths in version order:
  1. payload.id — all pre-v0.129.0 sessions (unchanged behaviour)
  2. payload.session_id — v0.129.0+ (PR #20437)
  3. payload.thread.sessionId — v0.129.0+ v2 API path (PR #21336)

src-tauri/src/parser/session.rs

• parse_session_meta_new: replaced str_field(payload, "id") with extract_session_id(payload).
• session_file_id: updated the session_meta arm to use extract_session_id so worker-session lookup also handles v0.129.0+ files correctly.

src-tauri/src/parser/discover.rs

• scan_session_file: replaced str_field(payload, "id") with extract_session_id(payload) so the lightweight discovery path is covered too.

Tests

9 new tests across the three touched modules:

Test	Location	Covers
extract_session_id_reads_id_field	entry.rs	Existing id path unchanged
extract_session_id_falls_back_to_session_id_field	entry.rs	v0.129.0 PR #20437 session_id field
extract_session_id_falls_back_to_thread_session_id	entry.rs	v0.129.0 PR #21336 thread.sessionId path
extract_session_id_prefers_id_over_session_id	entry.rs	Priority: id wins over session_id
extract_session_id_returns_empty_when_absent	entry.rs	Graceful empty result
parse_session_reads_id_from_session_id_field	session.rs	Full parse via session_id
parse_session_reads_id_from_thread_session_id	session.rs	Full parse via thread.sessionId
discover_sessions_reads_id_from_session_id_field	discover.rs	Discovery scan via session_id
discover_sessions_reads_id_from_thread_session_id	discover.rs	Discovery scan via thread.sessionId

Verification

cargo test --lib  →  68 passed, 0 failed
npx vitest run    → 122 passed, 0 failed
cargo clippy      →   0 warnings
cargo fmt         →   no changes