chore: fill in the 0.5.0 changelog from git history

[MikaAK]

Walked git log 523a121..main (the 0.4.9 version bump to now) and diffed every touched file against the 0.5.0 entry. Four commits landed in that range; three of them were only partly written up.

Commit	In the changelog before this PR
7ad44ee route sandbox_sleep_ms through Cache.Config	yes, under 0.4.9
043ddbe support Elixir 1.20 (#47)	no
9caae9c MultiLayer cross-node coherence (#49)	no
c7765ce adapter-aware term encoding (#48, includes #50 and #51)	yes, except the RefreshAhead half

Added

Features

• feat(multi_layer) — the Coordinator, the :pg group, broadcast_mode: :invalidate | :replicate, broadcast_layers, and the best-effort delivery contract (TTLs stay the correctness floor).
• feat — Elixir 1.20 support, including what changed in the generated code: one adapter_options!/1 clause per configured opts shape instead of a clause per shape plus a catch-all, and the {:error, _} branches 1.20 proves unreachable dropped from the generated get/1.

Performance

• Cache.RefreshAhead resolves encoding against the adapter it wraps, so RefreshAhead over ETS stops encoding too. Part of perf: stop encoding terms for adapters that store them natively #48, not previously written up.

Breaking Changes

• Minimum Elixir is now ~> 1.15, up from ~> 1.11. A consumer on 1.11 currently finds this out from a compile error.

Chores (new section)

• :credo 1.7.13 -> 1.7.18 in the lock — 1.7.13 crashes on 1.20's sigil token format, and the newer one flagged a length/1 > 0 check now written !== [].
• :faker dropped — it does not compile on 1.20 (raw U+0085 is a hard syntax error there); three random-string helpers moved to test/support.
• :preferred_cli_env moved into def cli/0.
• The RefreshAhead global-lock test race, which was the red Test run on main from 2026-08-02.

Coverage check

Every file changed since the 0.4.9 bump now maps to an entry:

cache.ex, term_encoder.ex, agent.ex, con_cache.ex, counter.ex, dets.ex, ets.ex, persistent_term.ex, redis.ex, sandbox.ex → the encoding entries. multi_layer.ex + multi_layer/coordinator.ex → the new feature entry. refresh_ahead.ex → the new perf line. mix.exs → the Elixir requirement and the Chores section. config.ex + sandbox_registry.ex → the existing 0.4.9 entry.

One thing to decide

Hex's latest published version is 0.4.8 — 0.4.9 was never tagged or released, so its section ships together with 0.5.0 whenever 0.5.0 goes out. Worth deciding whether to fold the 0.4.9 entry into 0.5.0 or leave both headings. I left them as they are.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.87%. Comparing base (c7765ce) to head (3db6b2b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #52   +/-   ##
=======================================
  Coverage   83.87%   83.87%           
=======================================
  Files          24       24           
  Lines         707      707           
=======================================
  Hits          593      593           
  Misses        114      114           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.