feat(content): bake and read flat collision assets

Append strict collision/topology payloads to the existing prepared package so later physics cutover can drop parsed DAT graphs without adding a second mapping or changing traversal behavior. The full 2,232,170-key catalog is deterministic across worker counts, exact-byte aliased, corruption-isolated, and cancellation-safe.

docs/architecture/acdream-architecture.md

@@ -173,6 +173,8 @@ src/
       TerrainSurface.cs       -> triangle-aware terrain contact (done)
       BSPQuery.cs             -> partial retail BSP dispatcher (active in L.2)
       TransitionTypes.cs      -> SpherePath / CollisionInfo / transition helpers (active in L.2)
+      FlatCollisionAssets.cs  -> immutable array/index collision schema (Slice I2)
+      FlatCollisionAssetBuilder.cs -> deterministic DAT graph preparation (Slice I2/I3)
       PhysicsDataCache.cs     -> GfxObj / Setup / CellStruct collision data (done, active)
       ShadowObjectRegistry.cs -> broadphase for nearby physics objects (active)
       PhysicsEngine.cs        -> ResolveWithTransition active player path

docs/architecture/worldbuilder-inventory.md

@@ -120,8 +120,9 @@ EnvCell, Surface, palette, and texture graphs during portals. The validated
 machine-local `acdream.pak` is opened through Content's
 `IPreparedAssetSource`; typed GfxObj and EnvCell requests deserialize immutable
 `ObjectMeshData` while retaining the existing App worker, staging, render-thread
-upload, cache, ownership, and shutdown contracts. The format-1/bake-tool-3
-payload persists exact batch translucency so App does not reconstruct a
+upload, cache, ownership, and shutdown contracts. The original
+format-1/bake-tool-3 render payload persists exact batch translucency so App
+does not reconstruct a
 `GfxObjMesh` for metadata. Setup activation uses the package TOC as an explicit
 type-presence index before reading valid Setup records through the bounded DAT
 cache. `DatPreparedAssetSource` and `MeshExtractor` remain explicit
@@ -131,6 +132,18 @@ bake/equivalence/UI-Studio tools, not a production fallback. Portal → HighRes
 installed-DAT gates are recorded in
 `docs/research/2026-07-24-slice-c-prepared-asset-cutover-report.md`.
 
+**Slice I3 prepared collision extension (2026-07-25).** The package remains
+format 1 and retains mesh type values 1–3; bake-tool 4 appends typed GfxObj,
+Setup, CellStruct, and EnvCell-topology collision payloads. Core owns the
+immutable flat records and deterministic raw-DAT flattener. Content owns the
+strict little-endian codec and `IPreparedCollisionSource`.
+`PakPreparedAssetSource` implements the render and collision interfaces over
+one mmap; it does not create a second DAT reader or mapping. CellStruct
+payloads alias only after exact serialized-byte comparison, while each
+EnvCell topology remains independently keyed. Production traversal is still
+the parsed graph oracle until Slice I6. Full-catalog evidence:
+`docs/research/2026-07-25-slice-i3-prepared-collision-package.md`.
+
 **Retail VFX hook compatibility seam (2026-07-14).** Chorizite.DatReaderWriter
 2.1.7 models `CreateBlockingParticleHook` as the common hook header only, while
 retail inherits the complete `CreateParticleHook` payload. The narrow readers in

docs/plans/2026-04-11-roadmap.md

@@ -1660,7 +1660,7 @@ port in any phase — no separate listing here.
 > `git revert ef1d263337997bb030eadb7b8e71d73dc659907a`. Slice H is complete:
 > retained UI/frame work, exact bounded light selection, and
 > pooled/borrowed/direct network I/O pass 8,292 Release tests / 5 skips and the
-> connected lifecycle/reconnect gate. Slice I is active at I3 from
+> connected lifecycle/reconnect gate. Slice I is active at I4 from
 > [its detailed plan](2026-07-25-modern-runtime-slice-i.md).
 
 **Spec:** `docs/superpowers/specs/2026-07-05-modern-pipeline-design.md` (the
@@ -1685,11 +1685,11 @@ hitch and follows.
 | MP1a | `AcDream.Content` extraction (GL-free MeshExtractor + boundary records out of App) | ✅ SHIPPED 2026-07-05 — user-gated (renders identical, zero tripwires, perf-neutral); 8 commits `651d041e`..`b0758d77` |
 | MP1b | Pak format + `acdream-bake` CLI + mmap `PakReader` + equivalence/full-scale gate | ✅ **SHIPPED 2026-07-24** — 729,888 EnvCell keys → 17,117 unique geometries + 712,771 aliases (42.6×), 751,141 total keys / 38,370 physical blobs, zero failures, 28,192.4 MiB, 81.4 s validated atomic publish; full-DAT gate also corrected a real collision in WB's legacy geometry hash. [Report](../research/2026-07-24-slice-b-full-bake-report.md) |
 | **MP-Alloc (safe batch)** | Reuse per-frame buffers: anim pose, particle draw-list, interior partition, animatedIds/drawableCells sets | ✅ SHIPPED + USER-GATED 2026-07-05 — dense-town frame-time spikes 20–87ms → 6–10ms, alloc spikes (30–75MB single-frame) eliminated, gen2 GC 5–11/window → ~0; user confirms FPS steady. 4 commits `b8c05e2b`..`91afea24` |
-| MP-Alloc (hard sites) | EnvCell settled-camera rebuild gate + physics `Transition` reuse | 🟡 Physics half SHIPPED 2026-07-25 — retail-shaped reset-complete transition/query scratch is bit-identical and 0 B/resolve across five profiles; immutable flat collision storage is defined and package integration continues in Slice I3. |
+| MP-Alloc (hard sites) | EnvCell settled-camera rebuild gate + physics `Transition` reuse | 🟡 Physics half SHIPPED 2026-07-25 — retail-shaped reset-complete transition/query scratch is bit-identical and 0 B/resolve across five profiles; immutable flat collision storage and its complete deterministic prepared package are shipped; traversal differential work continues in Slice I4. |
 | MP1c | Streaming cutover to pak + hitch gate | ✅ **SHIPPED 2026-07-24** — typed package-only production source, explicit Setup probes, non-allocating Portal-first lookup, exact translucency metadata, and ordered teardown; capped/uncapped/dense physical routes + user visual gate pass. Uncapped CPU p99 7.825→6.496 ms, GPU p99 3.406→2.706 ms, portal frame max 202.9→39.9 MiB, process allocation −41.8%, zero invalid Setup probes. [Report](../research/2026-07-24-slice-c-prepared-asset-cutover-report.md) |
 | MP2 | Retail particle distance/cell-view degradation: DAT-authored range, exact infinite/finite off-view update branches, emitter-first render scan, user-requested 2× default range | ✅ SHIPPED 2026-07-17 — Aerlinthe hotspot `0x32000223` resolves to retail 64m and defaults to 128m; landscape/entity streaming distance unchanged |
 | MP3 | Arch ECS render world + delta submission (the 300-FPS lever) | ⚪ — note: does NOT fix the steady-state GC churn (that's MP-Alloc); MP3 is the draw-submission throughput lever |
-| MP4 | Zero-alloc frame loop + flat physics data (residual, post-MP-Alloc) | 🟡 ACTIVE — Slice I1 zero-allocation transition scratch and I2 immutable flat collision schema shipped; I3 package serialization/bake is active. |
+| MP4 | Zero-alloc frame loop + flat physics data (residual, post-MP-Alloc) | 🟡 ACTIVE — Slice I1 zero-allocation transition scratch, I2 immutable schema, and I3 complete deterministic collision package shipped; I4 flat traversal shadow implementation is active. |
 | MP5 | Job-system parallelism | ⚪ stretch, evidence-gated |
 
 ---

docs/plans/2026-05-12-milestones.md

@@ -123,9 +123,13 @@ deterministic immutable physics/containment BSP, polygon, Setup, bounds, and
 EnvCell-topology records without cutting traversal over. Synthetic corruption
 gates and representative installed-DAT source identity pass bit-for-bit. The
 complete I2 Release gate is 3,826 App tests / 3 skips and 8,355 solution tests
-/ 5 skips.
+/ 5 skips. I3 appends four collision package types and a separate typed
+prepared-collision interface over the existing single mmap. Two complete
+29,908,271,024-byte bakes contain 2,232,170 keys with zero failures and the
+same SHA-256 across different worker counts; cancellation/corruption gates and
+8,371 solution tests / 5 skips pass.
 Slice H is complete: retained UI/frame work, exact bounded light selection,
-and pooled/borrowed/direct network I/O pass. Slice I is active at I3 under
+and pooled/borrowed/direct network I/O pass. Slice I is active at I4 under
 [`2026-07-25-modern-runtime-slice-i.md`](2026-07-25-modern-runtime-slice-i.md).
 The historical exact G4 visual rollback remains
 `git revert ef1d263337997bb030eadb7b8e71d73dc659907a`.

docs/plans/2026-07-24-modern-runtime-architecture.md

@@ -2,8 +2,8 @@
 
 **Date:** 2026-07-24
 
-**Status:** Slices A–H and I0–I2 are complete. Slices F–L were explicitly
-approved 2026-07-24; Slice I3 is active.
+**Status:** Slices A–H and I0–I3 are complete. Slices F–L were explicitly
+approved 2026-07-24; Slice I4 is active.
 
 **Scope:** Reconcile and sequence the existing Modern Pipeline (`MP`) and
 Linux/headless (`LH`) tracks using the 2026-07-24 connected performance audit.
@@ -1200,8 +1200,10 @@ grounded walkable-publication profiles each measure 0 B/resolve, while
 fresh-vs-reused output and body state remain bit-identical. I2 now supplies
 validated immutable flat collision records: synthetic and installed-DAT
 source identity, exact float bits, deterministic pre-order, and corruption
-tripwires pass without changing production traversal. I3 package
-serialization and complete-catalog baking are the current execution point.
+tripwires pass without changing production traversal. I3 now packages all
+flat collision/topology records through a shared typed mmap source: two
+complete 2,232,170-key bakes are byte-identical with zero failures. I4 flat
+traversal shadow implementation is the current execution point.
 Evidence:
 [`../research/2026-07-25-slice-g5-production-profile.md`](../research/2026-07-25-slice-g5-production-profile.md)
 and
@@ -1209,6 +1211,8 @@ and
 and
 [`../research/2026-07-25-slice-i2-flat-collision-schema.md`](../research/2026-07-25-slice-i2-flat-collision-schema.md)
 and
+[`../research/2026-07-25-slice-i3-prepared-collision-package.md`](../research/2026-07-25-slice-i3-prepared-collision-package.md)
+and
 [`2026-07-25-modern-runtime-slice-i.md`](2026-07-25-modern-runtime-slice-i.md).
 
 The intended order is therefore:
@@ -1222,7 +1226,7 @@ honest metrics + committed baselines        (A — exit criteria block C)
   -> incremental render scene               (F)
   -> delta GPU submission                   (G)
   -> residual frame cleanup                 (H-a, H-b, H-c)
-  -> flat collision assets                  (I — CURRENT at I3)
+  -> flat collision assets                  (I — CURRENT at I4)
   -> presentation-independent runtime       (J — §0.3 authorization)
   -> Linux/headless/multi-session           (K)
   -> evidence-gated GPU jobs                (L)

docs/plans/2026-07-25-modern-runtime-slice-i.md

@@ -1,7 +1,8 @@
 # Modern runtime Slice I — flat collision assets and zero-allocation physics
 
-**Status:** I0–I2 COMPLETE — retail oracle, zero-allocation transition
-scratch, and deterministic immutable collision records fixed; I3 active
+**Status:** I0–I3 COMPLETE — retail oracle, zero-allocation transition
+scratch, deterministic immutable collision records, and complete prepared
+package fixed; I4 active
 **Parent:** `2026-07-24-modern-runtime-architecture.md`, Slice I
 **Purpose:** remove parsed DAT object graphs and steady collision allocations
 without changing one retail collision decision, float, comparison, or traversal
@@ -176,7 +177,12 @@ Evidence:
 
 Gate: two independent bakes are byte-identical; every collision key required
 by the canonical route is present; a failed/cancelled bake cannot replace the
-last good pak.
+last good pak. **PASSED 2026-07-25:** two complete 29,908,271,024-byte bakes
+with different worker counts produced the same SHA-256 and 2,232,170 typed
+keys with zero failures. Strict serialization/corruption/cancellation gates,
+representative installed-package reads, Release build, and 8,371 solution
+tests / 5 skips pass. Production traversal remains graph-only. Evidence:
+[`../research/2026-07-25-slice-i3-prepared-collision-package.md`](../research/2026-07-25-slice-i3-prepared-collision-package.md).
 
 ### I4 — flat traversal shadow implementation
 

docs/research/2026-07-25-slice-i3-prepared-collision-package.md

@@ -0,0 +1,97 @@
+# Slice I3 — prepared flat-collision package
+
+**Date:** 2026-07-25
+**Scope:** Modern Runtime Slice I3 only
+**Behavioral boundary:** storage, serialization, bake, and prepared lookup;
+production collision traversal remains on the parsed-DAT graph oracle.
+
+## Result
+
+The existing format-1 `acdream.pak` now carries four appended asset types:
+
+| Numeric type | Payload |
+|---:|---|
+| 4 | GfxObj collision BSP, polygon table, bounding sphere, and visual bounds |
+| 5 | Setup cylinders, spheres, and movement dimensions |
+| 6 | reusable CellStruct physics BSP, containment BSP, and portal polygons |
+| 7 | independently keyed EnvCell portals, visibility, and `seen_outside` |
+
+The existing mesh type values 1–3 did not change. Bake-tool identity advanced
+from 3 to 4; the package binary container remains format 1.
+
+`FlatCollisionAssetSerializer` is a strict little-endian codec. It:
+
+- writes every `float` through `SingleToInt32Bits`;
+- retains node, polygon, vertex, Setup-shape, portal, and visible-cell order;
+- checks counts before allocation and validates combined byte requirements;
+- checks cancellation during large rows;
+- rejects wrong payload kinds, unsupported schema versions, non-zero reserved
+  bits, invalid enum/tree/range contracts, truncation, and trailing bytes;
+- remains behind the package entry CRC, so a CRC or structural fault marks
+  only that typed entry corrupt.
+
+`IPreparedCollisionSource` is separate from the render-only
+`IPreparedAssetSource` API. `PakPreparedAssetSource` implements both over the
+same `PakReader` and therefore maps the 29.9 GB immutable package once, not
+once per subsystem. Render and collision counters are independent.
+
+CellStruct collision geometry is addressed by every EnvCell source key. The
+bake emits ordinary TOC aliases within the same source group and across groups
+only after comparing the complete serialized payload bytes. Per-cell topology
+is always written under its own key and is never inferred from shared render
+geometry.
+
+## Complete installed-DAT bake
+
+Two independent full bakes used 16 and 7 workers:
+
+| Metric | Result |
+|---|---:|
+| GfxObj mesh keys | 15,318 |
+| Setup mesh keys | 5,935 |
+| EnvCell mesh keys | 729,888 |
+| GfxObj collision keys | 15,318 |
+| Setup collision keys | 5,935 |
+| CellStruct collision keys | 729,888 |
+| EnvCell topology keys | 729,888 |
+| Total typed keys | 2,232,170 |
+| Physical blobs | 781,196 |
+| Failures | 0 |
+| File bytes | 29,908,271,024 |
+| SHA-256 | `FEE8595D512DCB119C98B3D9911CDF9A905C97B624BCB826CEAF8DFD3F67269C` |
+
+Both complete files have identical length and SHA-256. Exact-byte
+deduplication produced:
+
+- 9,363 physical GfxObj collision blobs behind 15,318 keys;
+- 979 physical Setup collision blobs behind 5,935 keys;
+- 2,596 physical CellStruct collision blobs behind 729,888 keys.
+
+The 16-worker bake completed and validated in 107.5 seconds; the 7-worker bake
+completed and validated in 80.5 seconds. Peak bake-process memory was
+4.43–4.89 GB working set and 3.81–4.21 GB private. This is offline extraction
+state and is not mapped as committed client memory; the production source
+memory-maps the immutable file and pages only accessed ranges.
+
+The validated bake-tool-4 package was installed at the machine-local DAT
+location for subsequent Slice I gates.
+
+## Verification
+
+- strict codec round-trip and exact-float-bit tests for all four payloads;
+- every truncation of a representative payload rejected;
+- wrong-kind, negative/impossible count, trailing-byte, CRC, and valid-CRC
+  structural-corruption tests;
+- concurrent prepared reads and separate render/collision accounting;
+- raw-DAT versus current cached-source preparation on representative installed
+  GfxObjs, Setups, and EnvCells;
+- filtered 1/8- and 8/3-worker bake equivalence and exact alias tests;
+- complete installed package reads for representative GfxObj, Setup,
+  CellStruct, and EnvCell topology keys;
+- failed validation and timed cancellation preserve the last published file;
+- Release build: zero warnings;
+- complete Release suite: 8,371 passed / 5 skipped.
+
+No divergence-register row changes: no gameplay decision or traversal route
+changed. Slice I4 adds the flat traversal referee while the graph path remains
+authoritative.