diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..8a93fbf
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,75 @@
+# CLAUDE.md
+
+## What this repository is
+
+This is an extracted copy of the commercial game *Sulphur Memories: Alchemist*
+0.4.2 (LÖVE 11.5, Lua/LuaJIT) — **and the work here is a blind-accessibility mod
+for it, not game development.**
+
+Everything outside `accessibility/` is the vanilla game. Treat it as read-only
+reference material: you read it to find out how the game works, and you patch it
+only in the rare case the docs sanction. All mod code lives in `accessibility/`.
+
+If a request sounds like a game change ("make the journal readable", "the
+inventory doesn't work"), it almost always means **"a screen reader user cannot
+use this"** — the fix belongs in `accessibility/`, not in `states/` or `models/`.
+
+## Read this before doing anything
+
+`accessibility/docs/scratch.md` — a living handoff document. It carries the
+current state of play, confirmed decisions that should not be relitigated, the
+traps that have already cost real debugging time, and what is verified versus
+merely written. **Read it first, and update it before you finish.**
+
+Then `accessibility/docs/README.md` maps the rest: architecture, hooking
+strategy, the phased plan, open questions, decisions.
+
+`accessibility/README.md` is the *user-facing* manual — the key bindings the mod
+adds. Update it when you add or change a key.
+
+## Working agreements
+
+- **The user is blind.** Every verification must be describable in text. Never
+  rely on a screenshot, and never ask them to check something visually. Console
+  output and testbed transcripts are the evidence.
+- **Change as little game code as possible**, so the mod re-applies cleanly to
+  new game versions. Currently the entire game-side footprint is one line in
+  `main.lua`. Check it has not grown:
+  ```
+  git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore' ':!CLAUDE.md'
+  ```
+  It must stay `main.lua | 1 +`. The pristine tree is tagged `vanilla-0.4.2`.
+- **Speech must never throw.** A missing DLL degrades to silence; the game keeps
+  running. Wrappers call through to the original and return its results verbatim.
+- **Never reveal anything outside `FoV` / `rememberedFoV`.** The mod must not
+  become a cheat.
+
+`accessibility/docs/scratch.md` has the full invariant list; these are the ones
+worth knowing before you write a line.
+
+## Verify after any change
+
+```
+lua accessibility/tests/test_history.lua                      # pure Lua, instant
+rm -rf ~/AppData/Roaming/LOVE/Alchemist                       # clean save
+"C:/Program Files/LOVE/lovec.exe" . --a11y-test               # ~4 min
+```
+
+The testbed drives the real game by code and navigates by *reading focus* rather
+than counting keypresses. It has caught essentially every bug in this project, so
+run it — a change that looks obviously correct is exactly the kind that fails.
+
+**What matters is `0 failures`, not the check count**, which varies between runs
+because several blocks are conditional.
+
+Use `lovec.exe` (not `love.exe`) for a console. Every utterance is mirrored there
+as a `[speech]` line, so speech is verifiable from a log rather than only by ear:
+`!` interrupted, `*` immediate, ` ` queued.
+
+## If something mysteriously does not speak
+
+Run the game and read the startup self-test. It reports every patch and every
+descriptor probe. Most menu narration reads the game's file-local variables via
+`debug.getupvalue`, so a renamed local in a future game version shows up there as
+`PROBE BROKEN: no upvalue 'x'` rather than as silence three screens in.
+`ok (unset until opened)` is normal.
diff --git a/accessibility/docs/README.md b/accessibility/docs/README.md
index ea561fa..78b2900 100644
--- a/accessibility/docs/README.md
+++ b/accessibility/docs/README.md
@@ -23,7 +23,7 @@ history unit tests passing.
 **Game-file footprint: one line in `main.lua`.** Verify at any time:
 
 ```
-git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore'
+git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore' ':!CLAUDE.md'
 ```
 
 ## The three findings that shaped everything
diff --git a/accessibility/docs/scratch.md b/accessibility/docs/scratch.md
index 91b5d14..16fc304 100644
--- a/accessibility/docs/scratch.md
+++ b/accessibility/docs/scratch.md
@@ -543,7 +543,7 @@ augmented with distance/direction/passability. Then the surroundings explorer
 
 Verify this list is exhaustive at any time with:
 ```
-git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore'
+git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore' ':!CLAUDE.md'
 ```
 Currently: `main.lua | 1 +`.
 
@@ -581,7 +581,7 @@ exploration, wall tones, and keyboard+speech access to every screen.
 lua accessibility/tests/test_history.lua                        # pure Lua, instant
 rm -rf ~/AppData/Roaming/LOVE/Alchemist                         # clean save
 "C:/Program Files/LOVE/lovec.exe" . --a11y-test                 # ~4 min, 29 checks
-git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore'   # must stay: main.lua | 1 +
+git diff --stat vanilla-0.4.2 -- . ':!accessibility' ':!.gitignore' ':!CLAUDE.md'   # must stay: main.lua | 1 +
 ```
 
 ### The five traps (all cost real debugging time — don't rediscover them)