examples/war: polish pass + README entry + plan close-out

End-of-implementation polish for the War example after the
compiler bugs were fixed:

- Title state now calls draw_big_war_banner instead of inlining
  12 draws — same pixel output, fewer lines.
- P_WAR_BURY redraws the previous round's face-up cards while
  the noise thumps fire so the table doesn't look empty for
  24 frames between the WAR banner and the new face-ups.
- Drop draw_word_war from render.ne (orphaned by the BIG WAR
  metasprite).
- Refresh comments in background.ne (now references the real
  felt tile) and deal_state.ne (drop the stale FRAMES_DEAL_STEP
  reference now that the deal pace is hard-coded at 2 frames).
- README.md and examples/README.md gain a war row.
- PLAN.md marks every implementation step complete and records
  the design revisions made along the way.
- Refresh the war audio hash to match the new ROM (the title
  screen helper change shifts one frame of pulse-2 timing
  enough to flip the FNV-1a). The frame-180 PNG is unchanged.

https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z

examples/war/PLAN.md

@@ -177,31 +177,81 @@ Game modes (`0`/`1`/`2` players) are captured by two `bool` flags
 
 ## 7. Implementation steps
 
-The checkboxes below are updated as each step lands. A step is only
-marked complete after the compiler still produces a working ROM and
-the change visibly does what it's supposed to.
+All steps complete. The order they actually shipped in is below
+(the original 12-step plan got compressed once the early steps
+turned up enough compiler bugs to demand investigation in
+parallel).
 
-- [ ] Step 1: Skeleton — top-level file, empty included files, compiles.
-- [ ] Step 2: Palette, felt background, card-back tiles, static card
-      rendered on the table.
-- [ ] Step 3: Card-face tiles (ranks, suits, big pips) + draw_card_face
-      helper showing all 13 ranks × 4 suits.
-- [ ] Step 4: Deck data structures, RNG, shuffle, init + HUD digit
-      rendering.
-- [ ] Step 5: Title state (WAR banner, 3-option menu, cursor, music,
-      autopilot).
-- [ ] Step 6: Deal state (animated deal + flip sfx).
-- [ ] Step 7: Play state phase machine with card animations and sfx.
-- [ ] Step 8: War tie-break (banner + bury animation + WarFlash).
-- [ ] Step 9: Victory state (winner banner + fanfare + auto-return).
-- [ ] Step 10: Polish pass (timing, readability, sfx/music tuning).
-- [ ] Step 11: Rebuild war.nes, capture goldens, verify diff.
-- [ ] Step 12: Update README.md and examples/README.md.
-- [ ] Code review pass: read every file end-to-end, fix mistakes.
+- [x] Step 1: Skeleton — top-level file, every included file
+      filled with a real implementation, compiles cleanly.
+- [x] Step 2: Felt background — replaced the builtin-smiley
+      grid with a custom `TILE_FELT_BG` cross-hatch tile.
+- [x] Step 3: Card art — bold rank glyphs (1 tile each), small
+      corner suits, big centre pip halves, card-back lattice,
+      card frame helpers (`draw_card_face` / `draw_card_back`).
+- [x] Step 4: Deck data structures — circular buffers with
+      front/count cursors, packed `(rank << 4) | suit` cards,
+      Galois LFSR PRNG, bounded random-swap shuffle, deal/split.
+- [x] Step 5: Title state — BIG WAR banner, "CARD GAME"
+      subtitle, 3-line menu with cursor, blinking PRESS A,
+      title-music + autopilot.
+- [x] Step 6: Deal state — animated deal with FlipCard sfx and
+      growing deck-back stacks.
+- [x] Step 7: Play state phase machine — `match phase` over the
+      11 P_* phases, fly animation that doesn't overshoot, win
+      cues, debounced human input.
+- [x] Step 8: War tie-break — BIG WAR banner reused as a
+      strobing flash, ThudDown noise sfx for each buried card,
+      pot grows by 6 per side per war.
+- [x] Step 9: Victory state — staggered "PLAYER X / WINS"
+      banner, top-of-deck showcase card, builtin fanfare,
+      auto-return to Title.
+- [x] Step 10: Polish pass — bold sprite font, card-fly
+      timing/overshoot fix, P_WAR_BURY redraws the previous
+      face-ups, draw_word_war removed (was orphaned by the BIG
+      WAR helper), title state shares the BIG WAR helper.
+- [x] Step 11: Capture goldens, verify all 31 ROMs match, war
+      golden lands cleanly on a mid-fly-A frame at frame 180.
+- [x] Step 12: Update README.md and examples/README.md.
+- [x] Code review pass: read every file end-to-end, fix any
+      mistakes found.
+
+Two compiler bugs were discovered along the way and fixed in
+the same PR (E0506 too-many-params + the wide_hi map leak in IR
+lowering). Three more compiler limitations are documented in
+`COMPILER_BUGS.md` with workarounds in the war source for now.
 
 ---
 
 ## 8. Design revisions
 
-(Empty — will be updated in-flight if anything changes from the
-approved design.)
+A few things shifted from the approved plan:
+
+- **`arm_fly` is 4 params, not 6.** The 5th and 6th params
+  (`fly_card`, `fly_face_up`) are written to globals at every
+  call site instead, because the v0.1 ABI silently drops params
+  past the 4th. The 4-param limit now produces a clean E0506
+  diagnostic so future authors won't trip on it.
+- **`card` parameter in `card_rank` / `card_suit` / `draw_card_face`
+  was renamed to per-function unique names** to dodge the IR
+  lowering's shared-VarId issue documented in
+  `COMPILER_BUGS.md` §1b. Same for `wrap52`'s `v` and the
+  `push_back_*` helpers. `x` and `y` are still shared because
+  they sit at the same parameter position in every helper that
+  takes them, so the routed slot mapping is consistent.
+- **The `Playing` state's phase machine uses `match`, not a
+  flat if-chain.** The if-chain shape allowed two phases to run
+  in the same frame after a `set_phase` transition, which made
+  the card-fly animation overshoot its endpoint by `FLY_STEP`.
+  `match` runs only the first matching arm.
+- **Card frame outline tiles (`TILE_FRAME_TL`/`TR`/`BL`/`BR`)
+  are still allocated in the Tileset but unused.** The card
+  faces use the rank/suit/pip tiles directly with white card
+  bodies that visually separate from the dark felt — a card
+  frame would have made each tile cramped without much
+  readability gain. Constants are kept for layout stability;
+  the tiles themselves serve as a 4-tile reserve for future
+  art tweaks.
+- **The deal animation** is a single bouncing card-back, not a
+  full 52-card cascade. Cleaner and cheaper, and the FlipCard
+  click rhythm carries the "we're dealing!" feel by itself.

examples/war/background.ne

@@ -3,20 +3,17 @@
 // NEScript loads the *first* declared `background` into nametable 0
 // before rendering is enabled, so whatever this file declares is
 // visible on frame 0 of the ROM. We use a single felt-table
-// background: a solid dark-green field for the play area. All UI
-// (title banner, "PRESS A", win banners, etc.) is drawn on top via
-// sprites so we never pay the cost of a full mid-frame nametable
-// swap.
-//
-// Tile 0 is the linker's builtin smiley — we don't want that in the
-// game, but it's safe to leave in the top-left corner because the
-// whole nametable is painted with a blank tile. Use the legend's
-// `.` entry to map every visible cell to tile 0 then rely on
-// sub-palette 0 (forest/green/mint) making it look like felt.
+// background — every cell is the dedicated TILE_FELT_BG (tile 75
+// in the Tileset sprite, a sparse cross-hatch authored to look
+// like dk_green felt with mint flecks when rendered through bg
+// sub-palette 0). All UI (title banner, "PRESS A", win banners,
+// face-up cards, etc.) is drawn on top via sprites so we never
+// pay the cost of a full mid-frame nametable swap.
 //
 // The `palette_map:` field is omitted on purpose: every attribute
 // byte defaults to 0, which selects bg sub-palette 0 for every
-// metatile. That's the felt palette.
+// metatile. That's the felt palette declared in the top-level
+// war.ne (forest / green / mint over a dk_green universal).
 
 background Felt {
     legend {

examples/war/deal_state.ne

@@ -2,17 +2,16 @@
 //
 // Shuffles the deck on entry, then runs a brief dealing animation
 // before transitioning into Playing. The animation shows a single
-// face-down card sprite alternating between A's deck and B's deck
-// while a FlipCard sfx clicks on each dealt step. The deck counts
-// tick up alongside so it looks like the stacks are actually
-// growing.
+// face-down "in flight" card sprite alternating between A's deck
+// and B's deck while a FlipCard sfx clicks on each dealt step.
+// The deck counts tick up alongside so it looks like the stacks
+// are actually growing.
 //
-// This state is short (52 * FRAMES_DEAL_STEP / 2 = 104 frames per
-// full deal at FRAMES_DEAL_STEP = 4). The jsnes harness captures
-// at frame 180 so it will see roughly "halfway through the deal"
-// unless we accelerate things. We compromise by dealing one card
-// every 2 frames so the full deal lasts ~52 frames, giving
-// Playing time to show meaningful content before frame 180.
+// Pace: one dealt card every 2 frames → 104 frames for the full
+// 52-card deal. Combined with the title's 45-frame autopilot,
+// Playing starts at roughly frame 150, leaving ~30 frames before
+// the jsnes harness captures at frame 180 — enough for the
+// CPU-think delay and the start of A's first fly.
 
 state Deal {
     on enter {

examples/war/play_state.ne

@@ -246,6 +246,11 @@ state Playing {
                 }
             }
             P_WAR_BURY => {
+                // Keep the previous round's face-up pair on the
+                // table while the buries thump in — visually the
+                // tied cards stay lit until the new pair lands.
+                draw_card_face(PLAY_A_X, PLAY_Y, card_a)
+                draw_card_face(PLAY_B_X, PLAY_Y, card_b)
                 // Bury up to 3 face-down cards from each deck, then
                 // draw a new face-up pair. We don't animate each
                 // individual buried card; just play a noise thump

examples/war/render.ne

@@ -155,16 +155,6 @@ fun draw_word_wins(x: u8, y: u8) {
     draw_letter(dww_px, y, 18)  // S
 }
 
-// "WAR" — the centred flash during a tie-break.
-fun draw_word_war(x: u8, y: u8) {
-    var dwa_px: u8 = x
-    draw_letter(dwa_px, y, 22)  // W
-    dwa_px += 8
-    draw_letter(dwa_px, y, 0)   // A
-    dwa_px += 8
-    draw_letter(dwa_px, y, 17)  // R
-}
-
 // "PRESS" — used on the title screen.
 fun draw_word_press(x: u8, y: u8) {
     var dwr_px: u8 = x

examples/war/title_state.ne

@@ -31,31 +31,17 @@ state Title {
         }
 
         // ── Big "WAR" title banner ───────────────────────
-        // Each letter is a 2x2 block of 16x16 BIG tiles.
-        // Three letters at 16px wide + 4px gap = 16*3 + 4*2 = 56px;
-        // centred at x = (256 - 56)/2 = 100.
-        // y = 32 puts the banner in the top third of the screen.
-        // BIG W
-        draw Tileset at: (100,  32) frame: TILE_BIG_W_TL
-        draw Tileset at: (108,  32) frame: TILE_BIG_W_TR
-        draw Tileset at: (100,  40) frame: TILE_BIG_W_BL
-        draw Tileset at: (108,  40) frame: TILE_BIG_W_BR
-        // BIG A
-        draw Tileset at: (120,  32) frame: TILE_BIG_A_TL
-        draw Tileset at: (128,  32) frame: TILE_BIG_A_TR
-        draw Tileset at: (120,  40) frame: TILE_BIG_A_BL
-        draw Tileset at: (128,  40) frame: TILE_BIG_A_BR
-        // BIG R
-        draw Tileset at: (140,  32) frame: TILE_BIG_R_TL
-        draw Tileset at: (148,  32) frame: TILE_BIG_R_TR
-        draw Tileset at: (140,  40) frame: TILE_BIG_R_BL
-        draw Tileset at: (148,  40) frame: TILE_BIG_R_BR
+        // Three 16×16 metasprite letters (BIG W, A, R), drawn
+        // via the same helper the in-game tie-break uses. Each
+        // letter is 8px wide (BIG_*_TL / BIG_*_TR side-by-side);
+        // letters land at x = 100, 120, 140 with the helper's
+        // internal 20-px stride.
+        draw_big_war_banner(100, 32)
 
         // Subtitle "CARD GAME" in 8x8 font under the banner.
-        // 9 letters incl. the embedded space → 9 sprites per row,
-        // which over-runs the 8-per-scanline limit. Splitting the
-        // subtitle across two y rows (offset by 8px) keeps each
-        // scanline under the limit.
+        // 8 letter sprites at y=64 — exactly at the per-scanline
+        // limit. The space between "CARD" and "GAME" is just a
+        // skipped tile column, so it doesn't burn an OAM slot.
         draw_letter(96,  64, 2)    // C
         draw_letter(104, 64, 0)    // A
         draw_letter(112, 64, 17)   // R