…1646)

Follow-up to #1642. After landing the fold-first preflight, the next
question was whether preflight needs to exist at all — and on a 1M-context
provider it doesn't: post-response decideAfterUsage already folds at
75%, upstream tool-result caps prevent single-message blowups, and the
byte ceiling the preflight was originally guarding against is gone.
Converge on the Claude-Code-style single compaction path: one fold check
per turn, at turn start.

- Delete decidePreflight, mechanicalTruncate, related constants, the
  PreflightDecision interface, and the per-iter preflight block in step().
- Add a single turn-start check after the user message is appended:
  if local request estimate > TURN_START_FOLD_THRESHOLD (90%), fold once
  before the iter loop.
- No mechanical fallback. If fold can't shrink the log, the request goes
  out and DeepSeek's error surfaces to the user — honest beats silent
  re-compaction with worse semantics.
- Drop preflight i18n keys + delete tests/preflight.test.ts.

Net -393 lines. E2E (live DeepSeek) green across baseline, high-ratio
terminal turn, and turn-start fold scenarios.

…moved, persisted usage stats, plan dispatch gate

Headline themes:
- Desktop: bundle the CLI-hosted React dashboard, retire Tauri+Preact duplicate (#1418)
- Config: drop preset abstraction; flash/pro are direct model selections (#1657, #1630)
- Stats: persist cumulative usage to session meta + auto-restore on startup (#1667, #1680, #1643, #1628)
- Plans: editMode="plan" enforced at the ToolRegistry dispatch gate (#1681); step advance fix (#1629)
- Context: fold once at turn start, drop pre-flight + byte-ceiling (#1642, #1646); collapsible compacted card (#1649)
- Subagents: per-skill flash/pro override + Settings UI (#1632)
- Desktop polish: sidebar drag-resize (#1688), responsive collapse (#1585), copy/edit overlay + msg-history nav (#1645), Esc closes modal not turn (#1685), QQ tab isolation (#1672), DiffCard for edits (#1662), theme-aware highlighting (#1655), system events toggle (#1654/#1650), macOS TCC inheritance (#1614), dashboard.enabled (#1612)
- Dashboard polish: persistent session URL (#1586, #1589, #1599), theme-aware highlighting (#1664), IME confirm-enter guard (#1689), code-fence lang fix (#1677), vendor chunk split (#1587), markdown table h-scroll (#1562)
- TUI: Alt+S input stash/recall; static history isolated from input rerenders (#1635); legacy mouse drop (#1637, #1648); multi-edit gated in review (#1647)
- Diff: SplitDiff column border holds under CJK (#1686)
- MCP: workspace roots passed to servers (#1625); codeCommand honors mcpServers (#1603)
- Config plumbing: (baseUrl, apiKey) resolved as a tuple (#1658); stale model id self-heal (#1663)

See CHANGELOG for the full list.

…uncate (#1741)

Three changes that together cut per-turn CPU ~57% and steady-state RSS
~22% in the 200-turn fakeFetch probe (rss=256MB→181MB at log.len=800).

- bpeEncode: in-place splice instead of slice/spread rebuild on every
  merge, plus 8K-entry LRU cache. Repetitive tool output (padded
  payloads, identifiers in code) re-encodes the same byte-level chunks
  thousands of times per session; the cache caps that at ~400KB.

- estimateConversationTokens: drop the full formatDeepSeekPrompt
  rebuild + single bounded tokenize. Sum per-message bounded counts
  with a fixed template overhead, gated by a content-string-keyed
  4K-entry LRU. Same entry tokenizes once over its lifetime instead of
  once per turn. The estimate drives fold thresholds (50%/75% of ctx)
  where ±5% slop is harmless.

- truncateForModelByTokens: sample-based fast path. For inputs in the
  [maxTokens, maxTokens*4] range the old code unconditionally tokenized
  the full string (37% total CPU on the 200-turn probe). Now we use a
  2KB-sample estimate with a 1.15x safety margin; only borderline cases
  fall through to a precise tokenize.

Regression origin: #1642/#1646 collapsed the conditional preflight into
an unconditional estimateTurnStart that runs every turn, surfacing the
underlying tokenizer cost. The tokenizer itself has always been a
pure-TS BPE port without caching — fine when called rarely, expensive
when called on every turn against growing logs.

Also adds three probes that reproduce + measure:
- scripts/probe-mem-leak.mts — drives CacheFirstLoop through N turns
  with fakeFetch, samples RSS/heap/log
- scripts/probe-jobs-leak.mts — confirms JobRegistry's MAX_COMPLETED_JOBS
  cap actually evicts
- scripts/analyze-cpuprofile.mjs — flat self/total roll-up for any
  .cpuprofile produced by --cpu-prof or `reasonix code --profile`

Co-authored-by: reasonix <reasonix@deepseek.com>