Investigate selective memory/YYYY-MM-DD.md persistence failures (LEARNINGS.md writes succeed)

From 2026-05-25 reflection. Pattern: nightly reflection cron successfully appends to LEARNINGS.md but the corresponding memory/YYYY-MM-DD.md TL;DR file does not always land on disk. Confirmed misses: memory/2026-05-16.md, 2026-05-17.md, 2026-05-18.md, 2026-05-20.md, 2026-05-22.md (reconstructed by heartbeat), 2026-05-24.md (reconstructed by 5/25 reflection). Confirmed hits across the same window: LEARNINGS.md entries for 5/20, 5/21, 5/22, 5/23, 5/24, 5/25. Working theory: the selective persistence is destination-path scoped — long-form writes to LEARNINGS.md succeed via one code path; small writes to memory/ and memory/standups/ get dropped via another. Steps: 1) compare the file_write tool call shape in a successful LEARNINGS.md cron run vs a failed memory/ cron run from the same reflection session; 2) look for a gateway-level path allowlist or quota that treats the two differently; 3) if a real gateway bug, ping Victor with reproduction. Not urgent — the reflection content survives in LEARNINGS.md. Priority 4: log/forget loop closure, not customer impact.