docs: finalize v0.23.0 release notes

Co-authored-by: Alfonso [Magic Context] <288211368+alfonso-magic-context@users.noreply.github.com>

Author: ualtinok

.alfonso/release-notes/v0.23.0.md

@@ -6,7 +6,7 @@ A minor release with three themes: the context-reduction system was rebuilt arou
 
 **The agent maintains its own memories now.** `ctx_memory` grew `update`, `archive` (including batch archive in one call), and `merge` for the memories the agent already sees in its context — previously these were reserved for the background dreamer, so a wrong or outdated memory stayed wrong until the next maintenance run. Cross-project access stays locked down: an agent can only touch its own project's memories. Memory categories are now schema-enforced (the 5-category taxonomy), so invalid categories fail at validation instead of being silently rejected.
 
-**Context nudges are quieter and cache-safe.** The old chat-visible reminder messages are gone. In their place: a compact `<system-reminder>` appended to tool outputs when reclaimable context piles up (Channel 1), and a single one-shot escalation near the threshold (Channel 2) that's delivered only when a fresh measurement confirms it's still warranted — never on stale data. Subagents get the same self-management machinery now: they see §N§ tags and `ctx_reduce`, with a minimal guidance block, so long-running subagent sessions no longer balloon.
+**Context nudges are quieter and cache-safe.** The old chat-visible reminder messages are gone. In their place: a compact `<system-reminder>` appended to tool outputs when reclaimable context piles up (Channel 1), and a single one-shot escalation near the threshold (Channel 2) that's delivered mid-turn — between tool calls, while the pile is still growing — and only when a fresh measurement confirms it's still warranted, never on stale data. Channel 1 paces itself: the re-fire interval scales with the history budget, repeat reminders in the same severity band are suppressed, and the cycle resets once the pile actually shrinks — so a long turn sees a handful of escalating reminders instead of one per tool call. Subagents get the same self-management machinery now: they see §N§ tags and `ctx_reduce`, with a minimal guidance block, so long-running subagent sessions no longer balloon.
 
 **Emergency context recovery actually hits its target.** At ≥85% pressure the tiered emergency drop (T3 misc → T2 edit/search → T1 navigation tools, newest 20% of each tier reserved) replaces the old need-blind age-based drops — and its reclaim target is now computed from the full live tail, fixing a systematic under-eviction the audits caught. The routine `auto_drop_tool_age` / `drop_tool_structure` config knobs are removed (doctor cleans them up); reduction is the agent's job via `ctx_reduce`, with the tiered drop as the safety net.
 
@@ -37,6 +37,11 @@ Beyond the headline items, three blind audit rounds over this release's changes
 - A primary agent could merge another project's memories (now dreamer-only, like the rest of cross-project access).
 - Token-count math: ordinal gaps from malformed rows no longer drop valid messages from boundary sums; a literal `<EOT>`-like string in tool output no longer crashes tokenization.
 - Tool calls cleared by `ctx_reduce` could be stripped one pass too early, busting the prompt cache on a defer pass (frozen-watermark replay fixes it).
+- Routine history compaction can no longer cross the newest user message — the active prompt always survives a background historian pass intact.
+- The Channel-2 one-shot lease is crash-safe: a delivery interrupted mid-send (process kill, database contention) is recovered by a TTL-scoped heal instead of wedging the nudge off for the rest of the session.
+- Two processes opening the shared database at the same moment could race during the WAL journal-mode switch; the busy timeout now installs first.
+- One-shot notifications (upgrade reminder, context-limit alert) only mark themselves delivered after an actual send — a skipped or failed delivery retries on a later launch instead of being lost.
+- Sidekick (the `/ctx-aug` helper) is read-only on project memory now; `ctx_memory archive` rejects already-archived ids with a friendly error instead of silently re-archiving.
 
 ## Config changes