iw4L/docs/MAP-LOAD.md

Map load: what lives where

Three floors: disk (asset_transport), format (fastfile_* → the asset_iw4 IR), products (asset_* + assets). assets uses transport for disk access and its source lanes to compile format captures into products; fastfile_* knows the format and opens no files. Installing the match is session, not here.

console/ui `map` → session::lifecycle   SessionSwapRequest, tear the previous
                     occupancy down, then MapLoadApproved{request_id}
  → assets::match_load    start_match_load onto load_pool() (MatchLoadBusy),
                          poll_match_load → PreparedMatchReady
  → session::match_apply  apply_prepared_match → scene + SimWorld + MatchInstalled

Cancellation is MatchLoadAbort(request_id): the walk returns MatchLoadOutcome::Canceled at its next checkpoint, throwing nothing away. Failure is MapLoadFailed, from discovery and install; a request ends once. Startup and later load failures return to the main menu with a map error dialog; OK or Escape dismisses it. The log keeps the full error.

The walk: assets::session_load::load_prepared_match

The single entry point; the composition root sees no fastfile_* and no AssetSink. Inside are parallel walks on load_pool(): the archive, startup materials, common_mp, the IW5/T5/T6 weapon bundles, language zones. common_mp goes before the map — its techset tables are needed before build_world_draw. Output is MatchLoadOutcome::Ready with a PreparedMatch (world, one material population, clip, weapons, catalogs and PreparedMap).

A walk enqueues its own image plan the moment it is ready, and the catalog keeps one row per image name. Two plans resolving the same archive entry into the same payload share one decode; a name three games spell alike but fill differently is an override, not a duplicate, and load_jobs.csv (BENCH.md) counts the two apart. The per-game adapter is assets::lane (ZoneGame → iw4/iw5/t5/t6); a lane gap is a typed LaneGap, never silence.

ZoneLane::load_common_mp returns owned common builders and diagnostics. A lane whose preparation needs already assembled donors can retain a private, consumed-once CommonFamilyCompiler inside that result. The shared loader supplies owned weapon, material, FPV, world-model, projectile, animation and effect builders; compilation returns them together with dependency refusals. This stage finishes before the common set is published or cloned for a match. It is not invoked by frame execution.

T6 model/material/effect captures stay private to the T6 lane. Its compiler owns stand-in donor lookup, native technique linking, named texture adaptations, animation admission, weapon dressing and projectile binding. Missing model/effect donors return typed refusals, while accepted contributions and existing builders remain available; source conversion diagnostics remain in the load report. Other lanes finish these products within their existing common walk. All lanes publish through the same common-set and match installation path.

ZoneLane::load_world borrows the common FilmVisionCatalog immutably. The map's vision overrides a common vision, including a map parse error; a failed map parse does not silently fall back. Selection and the merged vision catalog belong to LoadedWorld output. Loading a map does not consume a caller's common vision entries.

These are CPU compilation contracts. They do not establish shader-port admission, decoded-media readiness, GPU residency or playable readiness. The existing common cache owns compiled builders under its path-based CommonKey; a retained key does not detect edits to source files in place. Such content needs a rebuilt common set. No per-family decoder payload escapes the deferred compiler, and changing source content must not reuse its captured payload with unrelated donor builders.

Installing it is session::match_apply. Preflight builds a MatchInstallPlan — mode, doors, objectives, scene conversion, drawable world — and publishes nothing until it hands one over. Commit publishes it, boots the sim and writes MatchInstalled. The authority then prepares bot navigation on load_pool() from a world snapshot; it reports BotNavigationReady with the world generation. Session owns readiness policy: dedicated advancement needs navigation; listen advancement also needs rendering unless headless. Graphical presentation and admission require generation-matched rendering and audio; headless policy bypasses those presentation services. Explicit silent audio satisfies that policy; missing or failed audio does not. Old completion reports cannot release a newer world, and renderer systems do not write the authority hold. Session also owns the local input predicate. The walk graph is cached (nav), keyed by the content digest with the bake's schema and hull, so the second start of a map reads it back instead of walking the grid again; a match teardown drops the in-memory copy, not the file.

MatchLoadOutcome::Ready is the CPU package, not render-ready. The loading screen also holds for GPU images, every queued pipeline (the HUD blood film is queued as soon as its material exists) and the first_person stage: every weapon's first-person materials admitted and compositions laid out (render_anim::PreparedFpv), and every body, world-weapon, map-model and projectile material plus the single-model DObjs (PreparedModelMaterials). Remote kits and dropped-item compositions are built at install. load ledger: in the log is one line per load of what was handed over or compiled new against what an earlier load left behind.

Cache, and poking it: iw4l-artifacts/cache/<kind>/<prefix>/<key>

Content-addressed leaf in asset_transport::artifact_cache (cache_get / cache_put, fnv1a64). A miss is silent — the caller computes the value anyway — and a hit must be the same bytes a miss would have written. The key names every input; if the encoder changed, bump the format word. Live kinds: mips, wgsl, localize, nav and xwma_pcm, whose miss is decoded by the native Rust T5 WMA2 decoder. IW4L_GAMES holds the game trees; no folder name is hardcoded. Live it is make map mp_boneyard (RUN.md), with stages in LoadProgress.