psxrecomp/ENHANCEMENTS.md

PSXRecomp — Enhancement-Tier Work (framework-wide)

Faithfulness is the foundation (CLAUDE.md Rule -1); this file tracks the enhancement layer built on top of it: renderers beyond the software reference, widescreen, load acceleration, etc. Per-game enhancement ideas live in each game repo's ENHANCEMENTS.md. Active framework bugs referenced here live in the game repos' ISSUES.md until a framework tracker exists.

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R1 — OpenGL renderer (2nd backend): PLAYABLE, flicker root-caused + fixed

Status as of 2026-07-03 (branch feat/renderer-finish, working tree, uncommitted):

• The long-standing intermittent black-frame flicker (MegaManX6Recomp ISSUES.md #7 — the reason MMX6 shipped with the software renderer) is root-caused and fixed. Mechanism (proven via the new present ring + gl_coh_ring correlation): flush_cpu_upload() merged all pending CPU→VRAM writes into ONE union bounding box; a frame with two disjoint uploads produced a union spanning the display framebuffers, which the flush painted from the stale CPU VRAM mirror (the FBO is authoritative under GL) — stomping live frames with black. Two black presents per incident (one per double-buffer parity). Software renderer is immune (CPU array is authoritative there), which is why it was the safe default.
• Fix: exact pending-rect list (16 rects; merge only when zero uncovered pixels are added; wrap-aware GP0(A0) transfers split into up to 4 exact rects; overflow → order-preserving flush-all). Merge rule proven by a 20k-randomized- rect host unit test (0 stale / 0 missing painted pixels).
• New always-on observability: gl_present_ring (every SwapWindow site records path taken, src/letterbox rects, glGetError, wall-ms, backbuffer + blit-source pixel samples) — the instrument that made the 1:1 black-capture correlation possible. Plus a debug-server fix: send_fmt silently truncated >64KB responses into unparseable JSON (broke big ring dumps); now heap-formats exactly.
• Validation: ~18-minute MMX6 GL attract soak, ~1600 window captures across 3+ full attract cycles — zero isolated black frames, zero GL errors, no other visual anomalies. Tomba1 build-gl rebuilt with the fix, boots clean (full Tomba1 attract soak still owed).

Validation COMPLETE (2026-07-03, both titles):

• MMX6: ~18-min attract soak, ~1600 window captures, zero isolated black frames (agent, ring-correlated).
• Tomba1: 24-iteration/720-capture attract soak (2 flags, both multi-frame FMV content cuts) + the definitive pass: 23,807 CONSECUTIVE presents (gapless, seq-verified) over a full attract cycle via gl_present_ring — ZERO isolated dark presents, zero GL errors. The capture-level flags do not exist at the swap level.

Remaining to close R1:

1. USER final validation at the MMX6 Rainy Turtloid standing-still spot (the original repro; MMX6 build-modern settings.toml is left on renderer="opengl").
2. Flip MMX6's shipping default software→opengl + close ISSUES.md #7.
3. The same union-upload bug exists in the Vulkan backend (see R2 item 1).

R1b — Native-wide (16:9) GL: perf collapse ROOT-CAUSED + FIXED, band flicker FIXED

Status 2026-07-03 (branch feat/renderer-finish, commits f5362f4..8b819eb):

• The 16:9 perf collapse (Tomba2 3D attract 60→12fps, MMX6 2D attract dips) was never a GPU problem. Stack-sampled (devkitPro gdb) in the wedge: the main thread lived in ws_backdrop_site_kind ← exec_one — under native-wide the dirty-RAM interpreter classified EVERY executed instruction as a possible backdrop rewrite site; the classifier rescans ±512 bytes on cache miss and its 256-slot direct-mapped cache (2 hot PCs 1 KB apart collide) thrashed on overlay working sets. Squash mode gates the whole path off — that is why ws_nw on=0 restored 60fps while every GPU theory (mirror FBO ping-pong, extra prims, present path) failed. The earlier "60ms scene GPU / 70us per prim" numbers were CPU-starvation-inflated GPU-timestamp gaps (the GPU idles between CPU-paced submissions inside the bracket) — treat GL timer numbers on a CPU-bound frame as suspect.
• Fixes (dbe7812 + 8b819eb): opcode pre-filter (only addu/or/addi/addiu can be rewrite sites) + 8192-slot full-PC-tagged caches + g_dirty_ram_code_gen invalidation (memory.c) + a per-entry SITE-WORD tag (revalidates the cached verdict against the live instruction word — plain-CPU-store overlay reloads never hit the page-marking hooks, and a stale verdict fires a GPR rewrite at the wrong instruction = guest corruption).
• Numbers: Tomba2 GL 16:9 attract (heavy scene, ~640-1100 prims) 72-95ms/frame → 17-21ms (p50 17.1ms, ~52-58fps); MMX6 GL 16:9 attract locked 16.7ms through demo stages (worst 10s window avg 25ms at stage-load transitions).
• Top/bottom band flicker (MMX6 16:9, user-visible) FIXED (a0b5843): the GL mirror pass scissored the FULL wide surface; the SW reference (rt_wide) only widens X and keeps the draw-area Y clip. Under MMX6's vertical double buffer (draw area alternates y=0/y=240, both bands in ONE wide surface) mirror draws bled across the band boundary and presented a frame late as edge flicker. Scissor is now full-width X / draw-area Y. Validated with 0.15s-interval capture bursts: top/bottom 16-row inter-frame instability is 0.26x/0.21x the scrolling middle band (edges quieter than content).
• Wide surfaces now carry a DEPTH24_STENCIL8 attachment (cfa79bb): the stencil-less wide FBO was a spec-gray target for the stencil-enabled mask fixup passes AND left the PSX mask-bit mirror silently no-op on the wide surface. (Its per-pass GPU "cost" measurements that motivated it were later shown starvation-inflated; the attachment stays for mask correctness.)
• New permanent instrumentation: frame_perf mirror split (GL_TIMESTAMP pairs per wide pass: mirror_gpu_ms / canon_gpu_ms / mirror_pass_us), CPU-side attribution (cpu_flush_ms, cpu_wide_ms, batches, wide target sets, wide FBO creations per frame), and gl_ws_ablate mode=0..3 (skip mirror / state-only / no-FBO-rebind ablations) — the toolchain that exonerated the GPU and named the CPU producer.
• MMX6 wedge incident (RESOLVED to one mechanism, poisoned overlay shards): during the session MMX6 hit fatal wedges — twice in the 16:9 attract (wild dispatch 0x21010001 / 0x0C008096) and then DETERMINISTICALLY at boot frame 2518 (unknown dispatch 0x80095098) at BOTH aspects. Timeline nailed it: the overlay self-heal wrote a fresh 001EA000 shard batch at 20:53, exactly when attract wedge #1 hit (shards hot-loaded mid-run); every boot after loads them and wedges at 2518; quarantining the batch (cache/.../cg4_0cec55ab.quarantine) restored clean boots + attract. Most plausible poison source: the INTERIM stale-verdict build (dbe7812 before the 8b819eb word tag) corrupted guest RAM at 16:9, and autocapture snapshotted the corrupted overlay bytes into the captures the shards were compiled from. Self-heal recaptures with the hardened build. NOT a ws-stack or renderer defect. Tomba2 16:9 soaked clean throughout.

R2 — Vulkan renderer (3rd backend): RENDERS GAMEPLAY AT SPEED, gaps cataloged

Status as of 2026-07-03 (same branch/tree; -DPSX_ENABLE_VULKAN=ON, SDK 1.4.341.1; feat/vulkan-renderer turned out to be already merged into master — only a 26-line build-guard needed salvaging from the retired _wt-vulkan worktree):

• Three bring-up bugs root-caused and fixed this session:
  1. Boot wedge: per-pixel GP0 uploads did 2 vkAllocateMemory + 2 vkQueueSubmit each (driver churn → minutes-long stall, watchdog abort). Fixed with GL-style deferred batched uploads.
  2. Shredded 3D: draws raced CPU rewrites of the persistently-mapped vertex buffer (69.5% pixel divergence vs software at the same guest frame). Fixed with sub-allocation cursors + firstVertex bases.
  3. Semi-transparency order violations (59.5% divergence): VK still had GL's retired whole-batch STP split; ported GL's current two-pass model (ordered color pass + color-masked stencil fixup; semi prims isolated).
• Verified (guest-frame-aligned VRAM diffs via the new frameshot.py tool + window captures): title pixel-identical to software; attract within 0.62% of the GL oracle; 60.5 fps sustained; vk_perf steady-state ~0-2 allocs and ≤6 submits/frame (was thousands). 24-bit FMV present path written (old one was provably black) but NOT yet verified on-screen.

Gap catalog (ranked, low→high effort):

1. Port the exact-rect pending-upload fix from GL DONE 2026-07-03: exact-rect list ported + VK-specific COALESCED flush (one staging pair + two submits per flush regardless of rect count; the naive per-rect port re-created the submit churn at 0.7 fps — VK pays per-submit where GL pays per-glTexSubImage2D). UP_RECTS_MAX=64 on VK so MDEC row-coalesced FMV frames fit in one flush. Verified: attract renders correctly at ~51 fps, vk_perf mostly-idle frames.
2. Verify FMV on-screen DONE 2026-07-03: Whoopee logo + intro CG movie render correctly on VK (window captures). NOTE Tomba2 movies are 15-bit MDEC->VRAM (upload path), NOT depth24 — the depth24 compose path remains no-regression- verified only; validate on a 24-bit title (MMX6 opening) later.
3. Cache the FMV present staging image DONE 2026-07-03: persistent image + mapped staging keyed by (w,h), freed on resize/shutdown (cpres cache).
4. DS barrier DONE 2026-07-03: explicit stencil-aspect self-barrier (late-tests write -> early-tests read|write) at every begin_geo_pass; layouts verified against the init transition chain + render pass (attachment-optimal throughout). 4b. NEW (minor): flush_cpu_upload allocates 2 stagings per flush — ~16/frame during MDEC FMV streaming only (~0 in gameplay). A sync-aware staging ring would zero it; low priority.
5. Native-wide (16:9) compositor DONE 2026-07-03 (0b23ea3): per-base_x wide surfaces (RGBA8 color + OWN stencil image + framebuffer on the SHARED render pass — every pipeline works unchanged, and the mask-bit stencil mirror is real on the wide surface from day one). The mirror is a second render pass appended to the SAME one-shot CB as each flushed batch (no extra submits); u_xoff/u_xhalf push constants (pre-plumbed in the shaders) carry the translation/wider clip. Mirror scissor = full-width X / DRAW-AREA Y (the GL band-bleed lesson applied from day one). wide_clear via ClearAttachments (color + stencil=bit15); full-screen overlay rects suppress the batch mirror and draw one full-wide-width rect (margins dim/fade). GPU-direct present blits the displayed band letterboxed at (4wide_w : 3native_w); vkb_render_wide_display readback backs the facade + debug dump. vk_perf gains wide/wclr counters. VALIDATED (Tomba2 build-vk, PSX_WS_FORCE_2D=1 — master Tomba2 has no sprite-tag hooks): 16:9 attract presents full-width (mine-cart demo captures), locks 60fps on normal scenes (frame_period p50 16.68ms), ~51-57fps on the heavy semi-prim scene (29 wide passes/frame); 4:3 unregressed (p50 18.1ms on the 452-flush semi-isolation scene — the pre-existing item-7 profile, wide counters 0). Margins show 4:3-culled geometry only — full margin content needs the cull-widened overlay cache (cg4_0cec55ab.ws-experiment, not installed on master).
6. SSAA scale >1 unvalidated on VK.
7. Semi-prim isolation perf (one draw per semi triangle; same cost as GL today).

Validation targets: MMX6 + Tomba2, agent does initial (window-capture series

• frame-aligned cross-backend diffs), user does final.

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R3 — Validation sweep + merge (2026-07-03, USER-DRIVEN)

Full 3-title x 3-config playthrough validation (agent launched each config windowed

• confirmed on-screen via window_capture; user drove input + gave the verdict):

Title	OpenGL 4:3	Vulkan 4:3	OpenGL 16:9
Tomba1	PASS	YELLOW	PASS
MMX6	PASS	YELLOW	YELLOW
Tomba2	PASS*	PASS*	FAIL*

* Tomba2 = experimental / not production-ready; not merge-blocking. (Vulkan 16:9 was intentionally skipped — user directive: all 16:9 in OpenGL only.)

Findings (tracked for the next work cycle):

• OpenGL 4:3 is the strong, shippable path on all titles. This is the win.
• Vulkan 4:3 = YELLOW everywhere (why it ships hidden/experimental):
  • Tomba2: sluggish FMV, minor speech-audio fidelity loss, in-game slowdown (possibly progressive), text boxes don't dismiss, HUD weapon icon renders in all 3 slots (only center should show).
  • Tomba1: minor horizontal bar artifact at top of the load screen; dwarf village sluggish (the known overlay-heavy scene; perf only, renders correct).
  • MMX6: significant slowdown in Rainy Turtloid's RAIN AREA even at 4:3 — VULKAN-SPECIFIC (on GL 4:3 it is subtle at most). Renders correct; perf only.
• OpenGL 16:9: Tomba1 clean PASS. MMX6 YELLOW (rain-area lag evident at 16:9; same Rainy Turtloid perf hot-spot). Tomba2 FAIL — widescreen does NOT engage (renders 4:3 pillarboxed in the wide window + slow); expected, master Tomba2 has no sprite-tag ws hooks (ws work parked at 4:3).

Policy gates confirmed already in-tree (no code change needed for the merge):

• Vulkan is hidden by default: launcher offers only Software<->OpenGL (launcher.cpp:347/776); PSX_ENABLE_VULKAN defaults OFF (runtime.cmake:484); runtime downgrades renderer=vulkan -> opengl when not compiled (main.cpp:2463). Vulkan stays a dev/CLI-only backend (--renderer vulkan on a VK-enabled build).
• Widescreen carries an EXPERIMENTAL tag in the RmlUi launcher (launcher.rml:362).

MERGED to master 2026-07-03 (runtime-only; codegen hash unchanged, no regen). Game pins bumped to the new psxrecomp master. No release builds cut (user directive).

Open follow-ups (next cycle): VK perf (MMX6 rain-area, dwarf village, Tomba2 in-game — likely the CPU-bound dirty-RAM ws classifier path and/or VK per-submit cost); VK correctness (Tomba2 persistent text boxes + 3-slot HUD icon; Tomba1 load bar artifact); Tomba2 widescreen sprite-tag hooks; MMX6 Rainy Turtloid perf even on GL 16:9; and the pending MMX6 shipping-default flip software->opengl to close MegaManX6Recomp ISSUES.md #7 (GL validated this session).

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W1 — Tomba2 16:9: USER-FLAGGED visible issues queue (2026-07-06, NOT STARTED)

User-prioritized alongside the P0 crash work (ISSUES.md #8). None of these have been investigated yet — this section is the work queue + every known lead. All Tomba2, GL 16:9, worktree _wt-tomba2-ipr / Tomba2Recomp build-t2.

W1.1 — Black background columns in 16:9 (P3; incl. beach area)

• Symptom: huge black regions where the 2D far backdrop should fill the wide margins (user Image 1: large black sky scene); also a ~24px black column in beach-village at game-x 85–109.
• Class: 2D far-backdrop doesn't cover the wide FBO edges.
• Prior art / leads:
  • [widescreen.bg2d] config (recompiler/src/config_loader.cpp:699).
  • Memory ws_backdrop_preload.md (Tomba1): far-backdrop void = early sprite-tagged 0x65 tile grid; fix = centre-stretch gated preload.
  • Memory ws_draw_census_8c.md (Tomba1 8C scene): void was GTE-3D driver FUN_8004db3c; fixed via depth-gated un-squash. The 8C draw-census ring is the attribution instrument (always-on; query, don't arm).
• Next step: per-scene attribution — which producer draws the sky strips, and why the wide margins get no tiles. Attract may cover some scenes; the beach needs navigation (user drive or save).

W1.2 — 4:3 object culling visible at wide edges (P2 cull widening)

• Symptom: objects pop in/out at the 4:3 boundary in 16:9 (world objects culled by game code against 4:3 screen extents).
• Ghidra cull sites already identified (tomba2_ram.bin; overlay addresses — validate per scene variant before wiring):
  • FUN_8003e030: sltiu 0x140 @ 0x8003E228
  • FUN_80069b6c: addiu +0xE6 @ 0x80069B84 + sltiu 0x1CD @ 0x80069B8C
  • 0x80110A08: addiu +0x80 / sltiu 0x101
• Fix shape: [widescreen.cull] bias_sites/range_sites per-game config (enhancement-tier per-game shims are legitimate here). Prior art: Ape bring-up used per-game cull imms (0x181) + signed idioms (slti/bltz) (memory ape_widescreen_bringup.md).

W1.3 — Dialogue-box text tearing in 16:9 (P4)

• Symptom: full-width dialogue text splits with gaps (user Image 2: "Water cam…e out from th…e faucet").
• Cause known: gpu.c ws_nw_hud thirds — left/right-third sprites are anchored apart for HUD proportion; full-width dialogue glyphs tear at the third boundaries. Needs a smarter anchor (e.g. detect wide text rows / dialogue-box association) rather than blanket thirds.

W1.4 — Beach-area framerate (P1 perf; also user-flagged)

• 2D isometric scenes run 0.42–0.70× (beach/village worst). The convergence blockers are FIXED (autocapture futility backoff + entry-based coverage in tools/compile_overlays.py — see handoff 2026-07-06); the campaign was interrupted by ISSUES.md #8 and should resume after it: expect 2D scenes to climb past 0.85 as coverage converges. Residual axes if short of ~1.0: per-block pump overhead (psx_check_interrupts ~2.6M calls/s), attract cycling. Measure ONLY with two freeze_check snapshots over a known wall interval (executed throughput = d(psx_cycle_count) − d(cycles_skipped)); phase_profile is a ring read and returns instantly.
• CAUTION: any pace numbers taken in diff mode before ISSUES.md #9's redesign lands are garbage (the wedged shadow silently disabled all native dispatch).

L1 — Load-time-toward-0 burndown (2026-07-14, ACTIVE — guinea pig: Tomba 1)

Full analysis + gates/kill criteria: docs/LOAD_TIME_ZERO.md (this branch, spike/load-time-zero). ChatGPT consult merged (thread "PSXrecomp workspace"). Already-settled items are NOT re-tried: turbo_loads (shipped, ~2x), disc_speed divisor 4x/instant (proven unsafe — MMX6 VSync-callback wedge), yield pumps r1/r2 (proven fatal — green-thread corruption), BIOS CD HLE (rejected — no landmine, no host win). The frame: wall = guest_time x host_cost_per_guest_sec; under turbo the window is emulation-throughput-bound, so the safe axis is host cost (multiplies with turbo), the risky axis is guest time.

Prioritized burndown (most agnostic + most likely beneficial first):

• L1.0 — E0 load_probe_v2: load-window decomposition on Tomba 1. 100% agnostic, zero risk, prices every bet below. Split a real pig-load window into guest time (seek / sector cadence / per-sector processing / explicit waits) and host time (native code / decompressors / interp / CD-event machinery / SPU / GPU / pump). Existing rings first (freeze_check, cdrom_bursts, dirty_ram_stats per_pc, phase_profile); extend rings only where attribution is blind. Decisive question: why only ~2x during a presentation-suppressed window? Thresholds: decomp ≥~40% host → shards serious; ≤~8% → kill shards; CD/event/SPU machinery dominates → L1.2; wall-clock limiter found → fix that first.
• L1.1 — Turbo hardening. (a) re-validate SDL pump under a live burst (fix appears in-tree: pump precedes the turbo early-return); (b) audio at the HOST SINK only (drop excess samples, crossfade on exit; never guest state); (c) root-cause MMX5 dev-tools+turbo 0xE10 boot wedge (foundation timing bug).
• L1.2 — Event-horizon acceleration + batched device ticking. Provably side-effect-free poll/idle regions jump to the next scheduled observable event with exact cycle credit + identical event ordering; devices advance to deadlines instead of per-block ticks. Attacks the ~2x ceiling directly; class-level, all titles inherit. Gate set from L1.0's poll/idle share. Shipped: deadline-based device servicing, six Tomba wait sites, and proof-gated generic idle skipping. Cross-game validation is queued at the end. Kill: <10% gain or ONE event-order divergence.
• L1.3 — Load-path overlay coverage (killed by gate). L1.0 measured zero in-window interpreter instructions, so there is no coverage win to buy.
• L1.4 — Data shards (rejected/quarantined): verify-only SHADOW mode, then replay. Gated on L1.0 (decomp ≥~20-25% host share). Correctness bar: temporal write visibility — replay sound only if IRQs-off across the window OR duration < next observable event.
• L1.5 — Authentic drive backlog (killed as acceleration). Passive deadline-vs-exposure probe measured 1,304/1,304 data sectors available on their exact scheduled cycle, then the intentional fixed 5,000-cycle INT1 presentation delay. Zero early/late sectors, holds, pending/lost INT1s, or overwrites: there is no artificial lateness for backlog/catch-up to remove.
• L1.6 — Seek-only latency probe (killed on Tomba). The measured New Game window issued zero seek commands. Read-start latency was only 7,676,928 / 298,130,657 cycles (2.57%); pause latency was 8.11% but is an authentic CPU-visible ordering contract, not a safe seek-speedup target.
• L1.7 — Phase-2 doors (open only with cause): per-title read speedup with XA/CDDA/MDEC exclusions; decompressor HLE (only via L1.4 failing for a named reason); load-transition state cache (the only true near-zero; needs thousands-of-frames differential validation).

Live status / decision ledger (Tomba 1, 2026-07-14):

Item	Verdict	Evidence / measured result
L1.0 decomposition	DONE	761 sectors, ~9.5 s baseline window; zero in-window interp; host/static execution dominated.
L1.1 turbo hardening	IMPLEMENTED ON TOMBA; CORPUS GATE OPEN	SDL pump remains before every turbo return; 4-frame engage + 6-frame release debounce passed live QA. Opt-in host-audio sink advances canonical SPU state while discarding only accelerated host output; Tomba listening QA passed after 1,100,752 discarded SPU frames.
L1.2 event horizon	IMPLEMENTED; CORPUS VALIDATION QUEUED	Production cycle advancement already batches device service at event/MMIO deadlines. Six configured PsyQ CD-wait sites delivered ~27% + ~9% stages. Generic idle-loop skip then cut warm bursts 0.53->0.34 s and 2.19->1.73 s, with 4,599 skips / 765M guest cycles and zero CD overwrites. Strictly per-game opt-in.
L1.3 overlay coverage	KILLED	Interpreter share was zero in the measured load window.
L1.4 asset/data replay	REJECTED FOR NOW	FUN_8003EF50 replay produced title/game texture corruption despite zero verifier failures: v1 temporal verifier is unsound. Data shards default off and artifacts removed.
Configurable warm CD routes (L1.7 read-speed branch)	ACCEPTED, STRICTLY PER-GAME OPT-IN	Framework accepts up to 16 strict LBA routes with mismatch fallback and consumer-paced IRQ/DMA. Only data-read cadence accelerates; XA/CDDA, seek, and motor timing remain authentic. Tomba multi-route regression: 3 matches, 1,944 accelerated sectors, zero overwrites. Legacy singular config is deprecated.
L1.5 authentic backlog	DONE / KILLED AS ACCELERATION	1,304/1,304 sectors exact-deadline; INT1 exposure exactly +5,000 cycles; zero holds, pending/lost, or overwrites.
L1.6 seek-only probe	DONE / KILLED ON TOMBA	Automated New Game: 0 seeks across 792 data sectors. Read-start latency was 2.57% of the data span, below the 10% gate. Pause was 8.11% but remains authentic because early completion is a known race/wedge class.
L1.7 state cache / broader HLE	DEFERRED	User excludes savestates; decompressor replay failed correctness.

Method, every experiment: measure first via always-on rings; start flag-gated; one per session; kill criterion written before code. idle_skip, warm CD routes, and the turbo host-audio sink are all strictly per-game opt-in. MMX6 remains the next corpus validation.

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W2 — Tomba 1 (SCUS-94236) 16:9: HUD at the true wide corners (DEFERRED 2026-07-10)

User ask: in native-wide 16:9, re-anchor the HUD to the wide corners (repositioned, never stretched). First attempt shipped and was REVERTED the same day (game.toml nw_hud_corners back to false; the framework machinery stays, inert + A/B-able). What was learned, so the next attempt starts ahead:

• Mechanism reused: [widescreen] nw_hud_corners (gpu.c ws_nw_hud_shift thirds translate, from the MMX4/5 campaign) + a new tag-title scoping: polys and lines never shift (world/characters), rect-family prims shift only when UNTAGGED. TCP ws_hud_mode {"tag_rects":0|1} A/Bs the tagged-rect gate live.
• What worked: vitality gauge + life-counter (untagged rects, fully inside one outer third) anchored flush to the wide corners, world untouched.
• Failure 1 — composite tear (same class as W1.3): the in-world dialogue box ("It's locked...") is a composite of untagged rects SPANNING zone boundaries: its left/right end caps sit in the outer thirds and get pulled to opposite screen edges while the text stays centred — the box visibly splits. A blanket per-prim thirds rule cannot ship; it needs composite-group awareness (e.g. group prims drawn adjacently in the packet arena / same OT bucket, shift a group only if the WHOLE group fits in one zone).
• Failure 2 — AP counter immobile: the AP composite (0x65/0x67 rects, x≈220-292, y≈8-12) renders through the TAGGED sprite funnel (0x8005E08C), so the untagged-only gate skips it. Census now records a tagged column (gpu.c WsCensusEntry) — verify with ws_census. Lifting the gate via ws_hud_mode shifts it, but then tagged world-anchored rects (collectible sprites) near edges would shift too — needs the same group/HUD-band discrimination as Failure 1 or a per-title HUD packet arena range (nw_left_hud_packet exists for exactly this; needs Tomba's HUD arena addresses from a census session: HUD prims live in the 0x000Bxxxx/0x000Cxxxx double-buffered packet arenas alongside everything else, so the range must come from finer addresses).
• Groundwork landed on feat/ws-2d-scene-pillarbox: census tagged column, ws_hud_mode live A/B, and the untagged-rect scoping that makes nw_hud_corners safe to experiment with on tag titles.