Summary

Backfills 8 [Unreleased] entries in CHANGELOG.md for PRs merged to main without a CHANGELOG update. These commits shipped to main between v0.1.9 (2026-04-13) and the 0.1.10 release preparation (#263), and their entries will land in the next release (0.1.11 / 0.2.0), not 0.1.10.

This is a follow-up hygiene PR to #263 (0.1.10 security release prep) and must merge before the release session's "UNRELEASED → date" commit, so that [Unreleased] reflects the full main state at tag time.

Scope

• CHANGELOG.md only.
• [Unreleased] Added: +4 bullets (feat(namespace): path-based policy rules for namespace auto-assignment #253, cli(init): surface non-default values preserved from previous config #254, cli(init): add --fresh to drop wizard-untouched config leftovers #255, feat(cli): add mm config unset for targeted override removal #259)
• [Unreleased] Fixed: +3 bullets (fix(config): coerce list[BaseSettings] on mutation path #257, fix(config): delta-only save against comparand to close fragment/env drag-in #258, fix(config): migrate remaining config.json writes to atomic _atomic_write_json #262)
• [Unreleased] Changed: +1 bullet (fix(config): drop default-valued fields on save to prevent silent leftover pins #256)
• [Unreleased] Docs: unchanged.
• [0.1.10] block (from docs(changelog): 0.1.10 security section and version bump #263): unchanged.

Net diff: +54 lines, 0 removals.

Classification rationale

Keep-a-changelog convention:

• Added (new features / CLI affordances): feat(namespace): path-based policy rules for namespace auto-assignment #253 (NamespacePolicyRule config list), cli(init): surface non-default values preserved from previous config #254 (wizard "Preserved" summary), cli(init): add --fresh to drop wizard-untouched config leftovers #255 (mm init --fresh), feat(cli): add mm config unset for targeted override removal #259 (mm config unset).
• Changed (behavior updates without user-visible regression): fix(config): drop default-valued fields on save to prevent silent leftover pins #256 (save drops default-valued fields).
• Fixed (bug fixes): fix(config): coerce list[BaseSettings] on mutation path #257 (list[BaseSettings] mutation-path coercion), fix(config): delta-only save against comparand to close fragment/env drag-in #258 (fragment/env drag-in on save), fix(config): migrate remaining config.json writes to atomic _atomic_write_json #262 (atomic config.json writes).

#256 and #258 are narratively linked (both improve save correctness via comparand-based drop); cross-reference is baked into the #258 bullet ("Extends #256's class-level default drop by broadening the comparand").

Sources

All 8 bullets drafted from gh pr view <N> --json title,body — no commit-subject paraphrase. Fact-checks performed:

• feat(namespace): path-based policy rules for namespace auto-assignment #253 touches packages/memtomem/src/memtomem/config.py (load path) — confirms fix(config): coerce list[BaseSettings] on mutation path #257 follow-up narrative.
• fix(config): delta-only save against comparand to close fragment/env drag-in #258 uses "REPLACE layer" as project convention for config.json precedence tier — term preserved.
• cli(init): add --fresh to drop wizard-untouched config leftovers #255 uses "canonical" (vs. user-added my_extension keys) as meaningful distinction — preserved.

Out of scope

• uv.lock: local working tree has memtomem entry at 0.1.10 (regenerated by uv run ruff during docs(changelog): 0.1.10 security section and version bump #263 validation); origin uv.lock still shows 0.1.9. This is a leftover from docs(changelog): 0.1.10 security section and version bump #263 (should have been included there). Tracked separately — not bundled here to keep this PR CHANGELOG-only.
• Version bump: already landed in docs(changelog): 0.1.10 security section and version bump #263.
• [0.1.10] block: already landed in docs(changelog): 0.1.10 security section and version bump #263.

Gate runs

ruff check / ruff format --check trivially pass (CHANGELOG-only text diff, no Python changes).