v1.2.16

Added

• context-window.py --explain — why the autocompact nudge is quiet, and what to set. hooks.autocompactNudge fails silently by design: when the window cannot be established it stays quiet, which is indistinguishable from "nothing to warn about". The new read-only diagnostic says which case you are in, names the source the window came from (env / settings / cache / model-default), and reports the threshold that follows from it. health runs it (new Step 7.55, only when the nudge is enabled) and setup passes on its hint when the user turns the nudge on.
• It answers the two questions people get wrong. The threshold is not the window: Claude Code compacts at window − min(max_output, 20000) − 13000, so asking for compaction at 460000 means setting 493000 — setting 460000 compacts at 427000. And a value above the model's context window does nothing: on a 200k model 460000 resolves to 200000, which looks identical to a working setting. Both are reported explicitly, the second as a clamped: true flag.

Changed

• mnemo still ships no default for autoCompactWindow, and this is now written down as a decision rather than an omission. It is Claude Code's setting, not mnemo's; measured against the model table in the runtime, 8 of 14 models have a 200k window where any larger value has no effect at all, while on the 6 native-1M models a "sensible" value would halve someone's usable context without being asked. mnemo reports what to set and never writes it.