Document the PCSX2 test setup

PCSX2 was set up and working but existed only in this machine's filesystem
and in people's heads, so every comparison looked like a one-off observation
rather than something re-runnable. The setup section in
docs/plan/pcsx2-verification.md now records where the emulator, the BIOS, the
disc, the savestates and the PINE socket are, how a state is captured, and
which command the disc integration tests need -- and AGENTS.md and README.md
point at it from their orientation sections. One operational detail worth
spelling out: the emulator's directory is lowercase (pcsx2), which is not
what people type.

AGENTS.md

@@ -132,6 +132,7 @@ Read these before working in an unfamiliar area:
 | `docs/plan/` | One file per subsystem, written **as work proceeds** |
 | `docs/formats/` | Format specs, written **as formats are reversed** |
 | `PROVENANCE.md` | Upstream projects we build on, and their licences |
+| `docs/plan/pcsx2-verification.md` | PCSX2 is set up on this machine, and how to run the comparison loop |
 | `vendor/reRAC/` | Pinned reference checkout (not tracked) |
 
 ## Crates

README.md

@@ -88,6 +88,12 @@ Visual and behavioural comparison against PCSX2, replaying recorded input and
 comparing frames, level by level. The PS2 float model is reproduced rather than
 approximated — see [`AGENTS.md`](AGENTS.md#2-reproduce-the-ps2-float-model).
 
+PCSX2 is installed and working on this machine; the comparison loop that reads
+the game's own memory over its debug protocol is up, and level 0's and level
+1's tfrag lighting are verified byte-exact against it. See
+[`docs/plan/pcsx2-verification.md`](docs/plan/pcsx2-verification.md) for the
+setup and how to run it.
+
 ## Credits and licensing
 
 This project learns from and is built on the work of others. Licences are

docs/plan/pcsx2-verification.md

@@ -121,6 +121,33 @@ invisible.
   `tools/trace/tests/` and test against that; no test may read a savestate, a
   dump or a live emulator.
 
+## The test setup
+
+PCSX2 is installed and working on this machine, so every comparison above can
+be re-run rather than being a one-off observation.
+
+| What | Where |
+|---|---|
+| Emulator | `~/Desktop/pcsx2/pcsx2-v2.8.2-linux-appimage-x64-Qt.AppImage` — the directory name is **lowercase** on disk |
+| Game disc | `~/Desktop/pcsx2/games/Ratchet & Clank - Going Commando.iso`; verified target `SCUS_972.68` v1.01 NTSC ([`docs/disc-identification.md`](../disc-identification.md)) |
+| Emulator config | `~/.config/PCSX2/` (`sstates`, `bios`, `memcards`, `inis`, `logs`) |
+| BIOS | extracted into `~/.config/PCSX2/bios/` |
+| Savestates | `~/.config/PCSX2/sstates/SCUS-97268 (38996035).NN.p2s`, `NN` = slot |
+| Unpacked disc | `~/Documents/gc-extracted/`, all 27 levels |
+| PINE socket | `$XDG_RUNTIME_DIR/pcsx2.sock` (`/run/user/1000/pcsx2.sock`), slot 28011 |
+
+The emulator boots the disc with `-fastboot`; a level takes about a minute
+from a cold start to reach. To capture a state manually, press F1 in-game (it
+lands in the slot's `.p2s`); to capture from a script, `gc-trace
+pine-savestate SLOT` asks the emulator to write one.
+
+The disc integration tests need the image, not the emulator:
+
+```sh
+GC_DISC="$HOME/Desktop/pcsx2/games/Ratchet & Clank - Going Commando.iso" \
+    cargo test --workspace
+```
+
 ## Running it
 
 ```sh