docs: client-perf analysis, bench harness and work journal

Everything the next agent needs to run the Phase 2 optimisation loop on a
machine that can launch the client:

- analysis/client-perf/: LEVERS (ranked levers + corrections), BENCH-MATRIX
  (world, scenes, config IDs, blocks B0-B14 with decision rules),
  PLAYER-TUNING, SPAWN-TUNING, research briefs, the jar scanner and its
  output, observed default configs, and proposed-configs/ (build.py
  generates tiers and bench variants and fails on unknown keys;
  apply_variant.py applies a variant and merges options.txt).
- analysis/client-perf/bench/onion-bench/: bench-world datapack (scene
  teleports, Create grid, mob pen, sound storm, 120 s teleport tour).
- analysis/audit/: the static recipe/dependency audit, including gen_fixes.py,
  which generates the shipped Paxi datapack and was never tracked.
- phase0/: per-machine measurement harness (Steam Deck, 7700K/1060,
  6700K/1080 Ti).
- .pi/journal.md: running work log; read it first.

All of it is packwizignored, so nothing here ships to players.

analysis/client-perf/README.md

@@ -0,0 +1,53 @@
+# Client performance analysis — Phase 1 (static baseline)
+
+Goal: map the **client-side optimisation surface** of Onion MC (212 mods, MC 1.21.1 /
+NeoForge 21.1.251) and rank the levers *before* benchmarking. Nothing here has been
+measured on a client yet; Phase 2 benchmarks it (see `../../phase0/` for the fleet harness).
+
+**Start with [`LEVERS.md`](LEVERS.md)**: the prioritised lever list, plus add and remove
+candidates.
+
+## Layout
+
+| Path | What |
+| --- | --- |
+| `LEVERS.md` | Synthesis: ranked levers, per-machine expectations, add/remove candidates, corrections |
+| `proposed-configs/` | **Phase 1b**: staged tuned configs (tiers + bench variants, generated by `build.py`) and the delivery-mechanism decision (README §1) |
+| `BENCH-MATRIX.md` | **Phase 1b**: the Phase 2 run sheet (world, scenes S1–S6, config IDs, blocks B0–B13, decision rules) |
+| `bench/onion-bench/` | Datapack for the bench world: scene teleports, `/fill` setups, sound storm, 120 s tour |
+| `SPAWN-TUNING.md` | Shipped server spawn tuning (Alex's Mobs, Fowl Play, Critters): evidence and the B14 measurement plan |
+| `PLAYER-TUNING.md` | **Phase 1b**: player guide (tiers, JVM/heap, shaders, resource packs, Deck) |
+| `data/jarscan-report.md` | Static scan of every pinned jar: per-frame mixins, per-frame event hooks, atlas/model/shader/sound payloads, entity counts |
+| `data/jarscan.json` | Raw scan output (re-generate, don't hand-edit) |
+| `data/observed-default-configs/` | Generated defaults from the last real client launch (2026-09-24, older 110-mod pack). Use these to see actual default values |
+| `research/r1-render-core.md` | Sodium / Iris + shaderpacks / Flywheel / ModernFix / ImmediatelyFast / EntityCulling / mipmaps |
+| `research/r2-dh-xaero.md` | Distant Horizons 3.3.2 client + Xaero's minimap / world map |
+| `research/r3-entity-animation.md` | EMF/ETF + Fresh Animations, GeckoLib, player animation mods, LambDynamicLights |
+| `research/r4-effects-audio-hud.md` | Sound Physics, AmbientSounds, Subtle Effects, Perception, WATUT, TF / Alex's Caves visuals, HUD mods |
+| `research/r5-candidate-mods.md` | Perf mods *not* in the pack (availability on NeoForge 1.21.1, compat, verdict) |
+| `research/r6-jvm-platform.md` | GC / heap / JVM, Mesa / NVIDIA driver, Steam Deck platform levers |
+| `research/r7-sable-create-client.md` | Sable / Aeronautics / SSRD / Create + Flywheel client cost |
+| `research/r8-sweep-content-mobs.md` | Known-issue sweep: mob and content mods |
+| `research/r9-sweep-libs-ui-misc.md` | Known-issue sweep: libraries, UI, misc client hooks |
+| `scripts/jarscan.py`, `scripts/report.py` | The scanner |
+| `scripts/jx.py` | Jar inspection without unzip/java: `ls`, `cat`, `str` (class-file string constants); nested jars as `outer.jar!inner.jar` |
+
+Re-run the scan after the mod set changes:
+
+```sh
+# jars: download every mods/*.pw.toml url into a dir (analysis/audit/fetch.py does this)
+python3 scripts/jarscan.py /tmp/onion/jars ../.. data/jarscan.json
+python3 scripts/report.py data/jarscan.json data/jarscan-report.md
+```
+
+## Method and confidence
+
+- **Static scan.** The scanner parses class-file annotations to get real `@Mixin` targets and
+  injector kinds. It reads constant pools for event-type references and PNG headers for
+  texture sizes, and it skips the Fabric-only payloads of multi-loader jars. The numbers are
+  *surface*, not cost: a mixin on `LevelRenderer` may be a one-line early-return.
+- **Research.** Nine subagent briefs (deepseek-v4.1-flash / glm-5.3-flash) are tagged
+  VERIFIED / DOCUMENTED / COMMUNITY / INFERENCE with URLs. Load-bearing claims were
+  spot-checked by the orchestrator. Corrections are listed in `LEVERS.md` §7.
+- **Observed defaults.** These come from the old Prism instance's generated configs. They
+  are the authoritative "what a player gets today" values for the mods that existed then.