2 files changed, 100 insertions, 0 deletions

diff --git a/docs/TESTING.md b/docs/TESTING.md
new file mode 100644
index 0000000..6cac6fa
--- /dev/null
+++ b/docs/TESTING.md
@@ -0,0 +1,52 @@
+# Testing
+
+## Automated suite
+
+```sh
+cargo test
+```
+
+The suite is deterministic and headless: no network, no PTY, no sleeps, no
+shared global database. Each test owns its state.
+
+| File | Covers |
+| --- | --- |
+| `tests/client_core.rs` | Client command/game flows via a headless screen applying logical effects. |
+| `tests/client_ui.rs` | Help, history, completion, bet parsing, display width, cursor math. |
+| `tests/protocol.rs` | Newline buffering and timeout/error classification. |
+| `tests/server_core.rs` | Handler, bcrypt migration, SQL injection, transaction rollback, `plays` audit, sessions. |
+| `tests/slots.rs` | Server slots payout rules and overflow handling. |
+| `tests/storage.rs` | Client/server SQLite storage helpers. |
+| `tests/tofu.rs` | SPKI fingerprint and TOFU decisions. |
+
+`tests/tofu.rs` shells out to `openssl`, so run it on a machine where the
+`openssl` CLI is available.
+
+## Manual TUI checklist
+
+There is no CI. Run this on Linux and on a Windows VM before a release.
+Use an 80-column terminal because several output lines are width-sensitive.
+
+1. Start the server with a valid `identity.p12`, then start the client.
+2. First contact prints three lines and the 64-character fingerprint does not
+   wrap at 80 columns. `Connected to ...` shows a one-decimal ping.
+3. `register` / `login`: backspace removes one `*` per key, Esc cancels the
+   prompt, Ctrl+C exits and restores the terminal.
+4. `help` fits 80 columns. Tab completion wraps within 76 columns and the
+   cursor stays visible.
+5. `play slots 50` shows `Bet: 50 PLN` and the fetched balance.
+6. Space shows `Spinning...`, then the reels, win text, and new balance inside
+   the same 7-line board. The controls line is never overwritten.
+7. `+` / `-` after a spin changes only the bet; no stale result lines appear.
+8. `q` clears the board. Ctrl+C in a game clears the board and exits.
+9. `info`, `ping`, `send hello`, and `hosts` print readable output; the host
+   fingerprint fits 80 columns.
+10. Windows: repeat 2-9 and confirm keys are not duplicated or printed twice.
+
+## Manual server checks
+
+- Register, log out, log in again (bcrypt path).
+- Log in with a pre-0.3 user row (legacy SHA-256) and confirm it still works;
+  the row is upgraded to bcrypt.
+- Spin several times and confirm `plays` grows by one row per spin while
+  `users.balance` changes by `winnings - bet`.
diff --git a/docs/adr/0001-testable-client-server-cores.md b/docs/adr/0001-testable-client-server-cores.md
new file mode 100644
index 0000000..2e3cd1e
--- /dev/null
+++ b/docs/adr/0001-testable-client-server-cores.md
@@ -0,0 +1,48 @@
+# 0001: Testable client and server cores
+
+Status: Accepted (2026-10-28)
+
+## Context
+
+The client and server started as binaries with their game logic and I/O mixed
+together. That made the TUI hard to reason about: a spin appended results below
+the board, a later bet change redrew at the wrong line, and none of it could be
+tested without a terminal. The server handler had the same problem: it owned
+static database and session state, so its security-sensitive paths could not be
+exercised from `tests/`.
+
+## Decision
+
+- The library (`src/lib.rs`) owns shared logic. `src/bin/client` and
+  `src/bin/server` are thin adapters for crossterm, TLS, environment variables,
+  and interactive prompts.
+- `client::core::ClientCore` owns input, history, commands, game state, and
+  pending replies. It returns `Effect`s (`Print`, `ReplaceRegion`, `ClearRegion`,
+  `SetPrompt`, `SendLine`, `Interactive`, ...). The binary applies them; the
+  tests apply them to a headless screen.
+- `server::core::ServerCore` owns message handling and receives an injected
+  `Connection`, `GameRegistry`, and bcrypt cost. The binary only owns the TLS
+  listener and per-connection thread.
+- Tests live in `tests/` and exercise the library. Pure UI math is tested
+  directly; terminal ANSI output is checked manually with `docs/TESTING.md`.
+  There are no PTY tests because they cannot cover Windows and `RULES.md`
+  requires identical behaviour on all platforms.
+- The client keeps sending its SHA-256 credential. The server stores
+  `bcrypt(credential)` and upgrades legacy SHA-256 rows on the first successful
+  login. This protects a stolen server database without changing the wire
+  protocol, but the client-side credential remains replayable if `client.db`
+  leaks.
+- Each settled spin writes a durable `plays` row in the same transaction as the
+  balance updates. The in-memory session is a transient guard and is removed
+  as soon as the spin settles or fails.
+
+## Consequences
+
+- Client flows and server security rules are testable without a terminal or a
+  network. A visual bug becomes an assertion about the headless screen.
+- The binaries have an extra translation layer (`Effect` application), and the
+  server opens a SQLite connection per client.
+- Terminal rendering still needs a manual Linux/Windows pass; the checklist is
+  in `docs/TESTING.md`.
+- Password storage is stronger, but not a full PAKE. A future MAJOR protocol
+  change can replace the replayable credential.