chore: merge main into user/agam/temporal, resolve changelog conflicts

Keep both temporal reasoning (2026-05-13) and memory decay (2026-05-08/05-04)
entries in highlights and platform changelogs. Also clean up algo-internal
language from the temporal highlights entry.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/changelog/platform.mdx

@@ -11,11 +11,17 @@ mode: "wide"
 - **Search:** Added `reference_date` support to anchor relative temporal queries for tests, backfills, and reproducible demos
 
 **Improvements:**
-- **Memory:** Temporal enrichment runs asynchronously by default after v3 writes and feeds retrieval ranking once available
 - **API:** Temporal reasoning preserves the normal client response shape for search and get-all results
 
 </Update>
 
+<Update label="2026-05-04" description="">
+
+**New Features:**
+- **Memory Decay:** Per-project search-time ranking bias that boosts recently-used memories and gently dampens stale ones. Opt-in via `decay` on the project endpoint; off by default. The scaling factor stays in `0.3×–1.5×`, the public `score` remains clamped to `[0, 1]`, and the bias never filters a candidate out. See [Memory Decay docs](/platform/features/memory-decay).
+
+</Update>
+
 <Update label="2026-04-16" description="">
 
 **Improvements:**