docs(backlog): archive 9 resolved tracks to RETRO.md + refile follow-ups

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

BACKLOG.md

@@ -21,6 +21,25 @@ against current code before acting (memory is point-in-time).
 
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+## ✅ RESOLVED 2026-06-20 → see `RETRO.md` (branch `feat/backlog-burndown`)
+
+Built + unit-verified this pass (full detail + commit table in `RETRO.md`). The
+matching bullets below are superseded; only the noted follow-ups remain live:
+
+- **G** turnId `/repo`↔`/repo2` collision + WorkspaceStateProbe newline fingerprint — `784accb`
+- **I** `.cs`/Godot-Mono symbols — `f715ffa`; structural `.tscn`/`.tres` validator — `0e251d6`
+- **A §4** EventStore latency probe (wired) + llama-server probe — `266bbf0` *(follow-up: llama probe live wiring)*
+- **B §6 + C-A3** `CritiqueFinding` type + calibration projection — `f783eed` *(follow-up: `CritiqueOutcomeCorrelatedEvent` producer)*
+- **C-A1** brief echo-back gate — `1df7af5` *(follow-up: `planner.md` brief_echo + `role_pipeline` metadata to activate)*
+- **C-A2** stage-level plan checkpointing — `1a1b5cc`
+- **B §4** architect contradiction-check (display-only) — `eae0a0c` *(follow-up: decision emit hook + in-session L3 embedding)*
+- **D** dedicated `SourceFetched`/`LowQualityExtraction` events — `b098d87`
+
+**Not yet started (verifiable, Kotlin):** B §5 reviewer static-first infra; D batch fetch-approval + dynamic egress allowlist; B §2 plan-derived diff manifest; G narration-lane lag; H freestyle follow-ups.
+**Blocked in this sandbox:** E tui-go items (Go toolchain absent); F live-QA gates + D §6 web approval client (need local model / SearXNG / network / GPU).
+
+---
+
 ## A. Observability spec — `docs/plans/2026-06-13-observability-spec.md`
 
 Metrics + CLI + TUI pane and the health backbone are shipped (fe94140, 4f6bfa8,