`readFirstLine` allocated a fixed 16 KB buffer, but Codex CLI 0.128+
embeds the entire base_instructions / system prompt in the
`session_meta` line, pushing it past 20 KB. When the buffer doesn't
catch a newline, `isValidCodexSession` rejects the session, so every
recent Codex session is silently excluded from totals.
Switch to a streaming readline read so the first line is captured
regardless of length, and add a regression test that creates a
40 KB session_meta payload.
Locally, this changes my 30-day Codex total from €267 (only ~half
of sessions parsed) to €878 (all sessions parsed).