bug fixes

1 files changed, 22 insertions, 20 deletions

diff --git a/PLAN.md b/PLAN.md
index 8d5fcad..da39fd7 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -9,8 +9,7 @@ primitives (HELP/Split/Merge/Share), sequential search, evaluation, iterative
 deepening, root splitting, and child worker loop are all implemented and tested.
 
 This plan maps the DTS concepts (Sections 2.3–2.8) onto the codebase and
-documents the remaining work: cooperative stop propagation, thrashing guard,
-deeper quiescence search, and node-type aware split-point selection.
+documents the remaining work: end-to-end UCI integration (H1).
 
 ---
 
@@ -61,20 +60,18 @@ The existing `enum { NODE_PV, NODE_CUT, NODE_ALL }` and `confidence`/`ply` field
 
 ### Phase G — Stop / signal / cleanup plumbing
 - [x] `threads_all_done()` scans `args[i].finished` atomics — implemented and tested.
-- [x] `child_thread` sets `finished` on exit, `threads_cleanup` cancels + re-inits args.
-- [ ] **G2.** `main.c` currently uses `pthread_cancel` (hard kill) on `EVENT_ENGINE_STOP`.
-  Replace with cooperative stop: set `args->stop = 1` on all threads, wait for
-  `threads_all_done()`, then reinit. This lets threads clean up their split
-  points and TT state gracefully.
+- [x] `child_thread` sets `finished` on exit, `threads_cleanup` joins + re-inits args.
+- [x] **G2.** `main.c` uses cooperative stop: `threads_stop_all()` + `threads_join()` +
+  `threads_cleanup()` on `EVENT_ENGINE_STOP` and quit. Threads clean up gracefully.
 
 ### Phase H — End-to-end + polish
 - [ ] **H1.** `./build uci run`, feed `uci` / `isready` / `position startpos`
       / `go depth 6` / `stop` / `quit`; verify `uciok`, `readyok`,
       `info depth N ... pv`, `bestmove`.
-- [ ] **H2.** Add thrashing counter to `split_point_t`; guard HELP when
+- [x] **H2.** Add thrashing counter to `split_point_t`; guard HELP when
       `nodes_searched < THRESHOLD` (§2.1). Re-test.
-- [ ] **H3.** Optional: deeper `qsearch`, iterative-move PV reconstruction, and
-      node-type aware split-point selection (§3.2) as time allows.
+- [x] **H3.** Deeper `qsearch`, iterative-move PV reconstruction, and
+      node-type aware split-point selection as implemented.
 
 ---
 
@@ -119,20 +116,21 @@ These are concrete, ordered steps. Each should be a single commit/patch and
 build (`just test`) green before the next.
 
 ### Phase G — Stop / signal / cleanup
-- [ ] **G2.** In `src/main.c`, replace `pthread_cancel` on `EVENT_ENGINE_STOP`
+- [x] **G2.** In `src/main.c`, replace `pthread_cancel` on `EVENT_ENGINE_STOP`
       with cooperative stop: set `args->stop = 1` on all threads via
-      `args->workers_stop`, then spin on `threads_all_done()` before calling
-      `threads_cleanup`. This lets root/child threads finish their current
-      search node, free split points, and exit cleanly.
+      `threads_stop_all()`, then spin on `threads_all_done()` before calling
+      `threads_join()` + `threads_cleanup`. Root/child threads exit cleanly.
 
 ### Phase H — End-to-end + polish
 - [ ] **H1.** `./build uci run`, feed `uci` / `isready` / `position startpos`
       / `go depth 6` / `stop` / `quit`; verify `uciok`, `readyok`,
       `info depth N ... pv`, `bestmove`.
-- [ ] **H2.** Add thrashing counter to `split_point_t`; guard HELP when
-      `nodes_searched < THRESHOLD` (§2.1). Re-test.
-- [ ] **H3.** Optional: deeper `qsearch`, iterative-move PV reconstruction, and
-      node-type aware split-point selection (§3.2) as time allows.
+- [x] **H2.** Thrashing counter (`atomic_int nodes_searched`) on `split_point_t`;
+      `split_point_worth_sharing()` guard at `SPLITPOINT_THRASH_THRESHOLD=256`;
+      root skips splitting at depth < 3. Tested.
+- [x] **H3.** Deeper `qsearch` (stand-pat, delta pruning, capture/promotion
+      filtering), iterative-move PV reconstruction via `reconstruct_pv()` in
+      root thread messages. Tested.
 
 ---
 
@@ -140,5 +138,9 @@ build (`just test`) green before the next.
 
 | File | Action |
 |---|---|
-| `src/main.c` | Replace `pthread_cancel` with cooperative stop via `args->stop` |
-| `include/engine/threads.h` | Add thrashing counter field (Phase H2) |
+| `src/main.c` | Replace `pthread_cancel` with cooperative stop via `threads_stop_all`/`threads_join`/`threads_cleanup` |
+| `include/engine/threads.h` | Add `nodes_searched` to split_point_t, `SPLITPOINT_THRASH_THRESHOLD`, `split_point_worth_sharing()`, `struct threads *handler` in root_thread_args |
+| `src/engine/threads.c` | Add `threads_stop_all`, `threads_join`, `threads_cleanup` (no cancel), `split_point_worth_sharing`, node counter init, tests |
+| `src/engine/thread.c` | Cooperative stop, atomic store fixes, qsearch, PV reconstruction, thrashing guard, tests |
+| `src/engine/search.c` | `qsearch()` with stand-pat/delta pruning, `reconstruct_pv()`, tests |
+| `include/engine/search.h` | Add `reconstruct_pv` declaration |