iris is the framework alone; the app is one crate in app-rust/

Iris: "the organization of the rust rewrite is a mess right now... there
shouldn't be anything related to the app inside of iris. Iris is supposed
to be the UI framework alone." And, on the crate count: "I'm confused why
the app only code needs more than one crate though."

Nine cargo workspaces become three, and the port's project code -- which
sat in five places, four of them inside the framework -- becomes one crate,
`ai-app`, in `app-rust/`:

  client-core                -> app-rust/src/client
  iris/transcript-ui         -> app-rust/src/ui
  iris/transcript-fixture    -> app-rust/src/ui/fixture.rs + tests/ + touch/
  iris/desktop-app           -> app-rust/src/desktop + src/bin_desktop.rs
  iris/android-app           -> app-rust/src/android + android-project/
  android-shell              -> app-rust/src/shell

iris/ keeps core, macro, the iris crate, tabs-ui and rig-input, and now
mentions no session, transcript, setup or server anywhere.

Only two of the old splits had a reason that survived reading. event-model
stays a crate at the repo root because server/ depends on it too, so a
crate is what makes the backend and the app agree by construction. The two
Android .so names looked like a hard constraint -- a package produces one
library artifact -- until P2 turned out to already plan merging those two
Android apps into one; both faces now come out of libai_app.so, picked
apart by features so `--no-default-features --features shell` keeps wgpu,
parley and iris out of the Compose app's APK. docs/RUST.md's "One app
crate" has the rest, including what each remaining feature is for.

DECISIONS.md and SUBAGENTS.md move into docs/ with everything else.

Verified: ./run-tests.sh and `cd iris && cargo test` green, clippy and fmt
clean in all five workspaces, `cargo ndk -t x86_64` links libai_app.so,
build-apk.sh produces an APK that installs and launches on this checkout's
emulator (Gl ... virgl, as expected), and the phone-sized headless
screenshot renders the transcript unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app-rust/src/client/config.rs

@@ -0,0 +1,368 @@
+//! What a Rust client needs to reach one enrolled server: host, port and
+//! bearer token. Mirrors the shape `ServerConfig.kt`/`Api.kt`'s
+//! `handleEnrollment` parses out of an `aiapp://enroll?host=H&port=P&token=T`
+//! deep link -- the exact link `wg-app-link`'s `enroll` module mints and
+//! `app/ui-sandbox.sh`'s banner prints, so any Rust client can enrol from
+//! the same text a phone would scan as a QR, with no second format
+//! invented for it (RUST.md's E4).
+//!
+//! [`EnrollmentStore`] persists one of these as JSON, owner-only, in a
+//! directory the caller names -- `$XDG_CONFIG_HOME/ai-app-desktop` for the
+//! desktop app, the app-private files directory on Android. **Which**
+//! directory is the only part left to the platform: the format, the file
+//! mode and the "nothing saved yet is not an error" answer are the same on
+//! both, and were written twice before this.
+//!
+//! JSON rather than the project's usual RON: `wg-app-link`'s RON house
+//! rules (`format`) are for configs a person hand-edits, and this file
+//! never is one -- only the app itself writes or reads it.
+
+use base64::Engine;
+use serde::{Deserialize, Serialize};
+use std::io;
+use std::path::{Path, PathBuf};
+
+/// One enrolled server: reachable at `https://{host}:{port}`, authenticated
+/// with `token` as a bearer header.
+///
+/// `ca_pem` is the trust anchor to pin, when the link carried one (the
+/// `ca` parameter, `wg_app_link::enroll::ca_param`). It is optional
+/// because an app built on the machine its server runs on pins the CA at
+/// build time and needs nothing from the link; one built elsewhere -- the
+/// iris Android client is cross-compiled in a VM and run against the
+/// host's server -- has no other way to get it. A public certificate
+/// rather than a secret, so it costs the link nothing but length.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct EnrolledServer {
+    pub host: String,
+    pub port: u16,
+    pub token: String,
+    /// `#[serde(default)]` so an enrollment saved before this field
+    /// existed still loads, as the enrolled server it always was.
+    #[serde(default)]
+    pub ca_pem: Option<String>,
+}
+
+impl EnrolledServer {
+    /// Parses `aiapp://enroll?host=H&port=P&token=T[&ca=B]` (query order
+    /// does not matter; unrecognised keys are ignored). `token` is
+    /// percent-decoded, since `ui-sandbox.sh` encodes it precisely because
+    /// a raw token can contain `+`, which turns into a space if left to a
+    /// naive splitter.
+    ///
+    /// `ca` is base64url of the certificate's DER and is rebuilt into PEM
+    /// here, because that is what every consumer of it wants
+    /// (`UreqTransport::new`, and the file a person points `curl --cacert`
+    /// at). A `ca` that does not decode fails the whole link rather than
+    /// enrolling a server with no trust anchor: the link said which
+    /// certificate to pin, and quietly not pinning it is the one outcome
+    /// nothing downstream could notice.
+    pub fn parse_link(link: &str) -> Result<Self, String> {
+        let query = link.split_once('?').map(|(_, q)| q).ok_or_else(|| {
+            format!(
+                "'{link}' has no query string (expected \
+                 aiapp://enroll?host=...&port=...&token=...)"
+            )
+        })?;
+
+        let mut host = None;
+        let mut port = None;
+        let mut token = None;
+        let mut ca = None;
+        for pair in query.split('&') {
+            let Some((key, value)) = pair.split_once('=') else {
+                continue;
+            };
+            let value = percent_decode(value);
+            match key {
+                "host" => host = Some(value),
+                "port" => port = Some(value),
+                "token" => token = Some(value),
+                "ca" => ca = Some(value),
+                _ => {}
+            }
+        }
+
+        let host = host.ok_or_else(|| format!("'{link}' is missing 'host'"))?;
+        let port_str = port.ok_or_else(|| format!("'{link}' is missing 'port'"))?;
+        let port: u16 = port_str
+            .parse()
+            .map_err(|e| format!("'{link}''s port ('{port_str}') is not a number: {e}"))?;
+        let token = token.ok_or_else(|| format!("'{link}' is missing 'token'"))?;
+        let ca_pem = ca.map(|ca| pem_from_link_param(&ca)).transpose()?;
+
+        Ok(Self {
+            host,
+            port,
+            token,
+            ca_pem,
+        })
+    }
+
+    /// Where a `crate::client::api::UreqTransport` reaches this server.
+    pub fn base_url(&self) -> String {
+        format!("https://{}:{}", self.host, self.port)
+    }
+}
+
+/// The `ca` parameter (base64url of DER, unpadded) as a PEM certificate.
+fn pem_from_link_param(ca: &str) -> Result<String, String> {
+    let der = base64::engine::general_purpose::URL_SAFE_NO_PAD
+        .decode(ca.as_bytes())
+        .map_err(|e| format!("the link's 'ca' is not base64url ({e})"))?;
+    let body = base64::engine::general_purpose::STANDARD.encode(&der);
+    let mut pem = String::from("-----BEGIN CERTIFICATE-----\n");
+    for line in body.as_bytes().chunks(64) {
+        pem.push_str(std::str::from_utf8(line).expect("base64 is ASCII"));
+        pem.push('\n');
+    }
+    pem.push_str("-----END CERTIFICATE-----\n");
+    Ok(pem)
+}
+
+/// Where one client keeps the enrollment it should not have to be told
+/// about a second time. `dir` is the caller's, because that is the only
+/// part that differs by platform -- see this module's doc.
+pub struct EnrollmentStore {
+    dir: PathBuf,
+}
+
+impl EnrollmentStore {
+    pub fn new(dir: impl Into<PathBuf>) -> Self {
+        Self { dir: dir.into() }
+    }
+
+    pub fn dir(&self) -> &Path {
+        &self.dir
+    }
+
+    fn file(&self) -> PathBuf {
+        self.dir.join("enrollment.json")
+    }
+
+    /// Writes `server` under `dir`, creating it if needed, and sets the
+    /// file owner-only -- it carries a bearer token, the same reason
+    /// `server/`'s own token store is 0600.
+    pub fn save(&self, server: &EnrolledServer) -> io::Result<()> {
+        std::fs::create_dir_all(&self.dir)?;
+        let path = self.file();
+        let json = serde_json::to_vec_pretty(server)
+            .expect("EnrolledServer holds nothing that fails to serialise");
+        std::fs::write(&path, json)?;
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            std::fs::set_permissions(&path, std::fs::Permissions::from_mode(0o600))?;
+        }
+        Ok(())
+    }
+
+    /// `Ok(None)` when nothing has been enrolled yet, rather than an error
+    /// -- "not enrolled" is an ordinary first-run state, not a failure
+    /// (UI_RULES' "a deliberate choice is not a problem to report" applies
+    /// just as well to a file that simply hasn't been written yet).
+    pub fn load(&self) -> io::Result<Option<EnrolledServer>> {
+        let path = self.file();
+        match std::fs::read(&path) {
+            Ok(bytes) => {
+                let server = serde_json::from_slice(&bytes).map_err(|e| {
+                    io::Error::new(
+                        io::ErrorKind::InvalidData,
+                        format!("{} is not a valid enrollment ({e})", path.display()),
+                    )
+                })?;
+                Ok(Some(server))
+            }
+            Err(e) if e.kind() == io::ErrorKind::NotFound => Ok(None),
+            Err(e) => Err(e),
+        }
+    }
+}
+
+fn percent_decode(s: &str) -> String {
+    let bytes = s.as_bytes();
+    let mut out = Vec::with_capacity(bytes.len());
+    let mut i = 0;
+    while i < bytes.len() {
+        if bytes[i] == b'%'
+            && i + 2 < bytes.len()
+            && let Ok(byte) =
+                u8::from_str_radix(std::str::from_utf8(&bytes[i + 1..i + 3]).unwrap_or(""), 16)
+        {
+            out.push(byte);
+            i += 3;
+            continue;
+        }
+        out.push(bytes[i]);
+        i += 1;
+    }
+    String::from_utf8_lossy(&out).into_owned()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_host_port_and_token() {
+        let server =
+            EnrolledServer::parse_link("aiapp://enroll?host=127.0.0.1&port=8547&token=abcDEF123")
+                .unwrap();
+        assert_eq!(
+            server,
+            EnrolledServer {
+                host: "127.0.0.1".to_string(),
+                port: 8547,
+                token: "abcDEF123".to_string(),
+                ca_pem: None,
+            }
+        );
+        assert_eq!(server.base_url(), "https://127.0.0.1:8547");
+    }
+
+    #[test]
+    fn field_order_does_not_matter() {
+        let server =
+            EnrolledServer::parse_link("aiapp://enroll?token=tok&port=443&host=example.com")
+                .unwrap();
+        assert_eq!(server.host, "example.com");
+        assert_eq!(server.port, 443);
+        assert_eq!(server.token, "tok");
+    }
+
+    #[test]
+    fn a_percent_encoded_token_is_decoded() {
+        // ui-sandbox.sh's own reason for encoding: a raw '+' would
+        // otherwise arrive as a space.
+        let server =
+            EnrolledServer::parse_link("aiapp://enroll?host=h&port=1&token=a%2Bb%2Fc").unwrap();
+        assert_eq!(server.token, "a+b/c");
+    }
+
+    #[test]
+    fn a_missing_field_is_named_in_the_error() {
+        let err = EnrolledServer::parse_link("aiapp://enroll?host=h&port=1").unwrap_err();
+        assert!(
+            err.contains("token"),
+            "error should name the missing field: {err}"
+        );
+    }
+
+    /// The CA travels as base64url of the DER and comes back out as the
+    /// PEM every consumer of it wants -- the same round trip
+    /// `wg_app_link::enroll::ca_param` mints.
+    #[test]
+    fn a_ca_in_the_link_comes_back_as_pem() {
+        let der = [0x30u8, 0x82, 0x01, 0xfb, 0x3e, 0x7f];
+        let param = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(der);
+        let server =
+            EnrolledServer::parse_link(&format!("aiapp://enroll?host=h&port=1&token=t&ca={param}"))
+                .unwrap();
+        let pem = server.ca_pem.expect("the link carried a CA");
+        assert!(pem.starts_with("-----BEGIN CERTIFICATE-----\n"), "{pem}");
+        assert!(
+            pem.trim_end().ends_with("-----END CERTIFICATE-----"),
+            "{pem}"
+        );
+        assert_eq!(
+            base64::engine::general_purpose::STANDARD
+                .decode(
+                    pem.lines()
+                        .filter(|l| !l.starts_with("-----"))
+                        .collect::<String>()
+                )
+                .unwrap(),
+            der
+        );
+    }
+
+    /// A link with no `ca` is an ordinary link, not a broken one: an app
+    /// that pins at build time mints and reads exactly these.
+    #[test]
+    fn no_ca_parameter_is_none_not_an_error() {
+        let server = EnrolledServer::parse_link("aiapp://enroll?host=h&port=1&token=t").unwrap();
+        assert_eq!(server.ca_pem, None);
+    }
+
+    /// The half that cannot be noticed later: a `ca` that does not decode
+    /// must fail the link rather than enrolling with nothing pinned.
+    #[test]
+    fn a_ca_that_does_not_decode_fails_the_link() {
+        let err =
+            EnrolledServer::parse_link("aiapp://enroll?host=h&port=1&token=t&ca=not!base64url")
+                .unwrap_err();
+        assert!(err.contains("ca"), "{err}");
+    }
+
+    #[test]
+    fn a_saved_enrollment_reads_back_the_same() {
+        let dir = tempfile::tempdir().unwrap();
+        let store = EnrollmentStore::new(dir.path());
+        let server = EnrolledServer {
+            host: "127.0.0.1".to_string(),
+            port: 8547,
+            token: "tok".to_string(),
+            ca_pem: Some("-----BEGIN CERTIFICATE-----\nQUJD\n-----END CERTIFICATE-----\n".into()),
+        };
+        store.save(&server).unwrap();
+        assert_eq!(store.load().unwrap(), Some(server));
+    }
+
+    #[test]
+    fn nothing_saved_yet_is_none_not_an_error() {
+        let dir = tempfile::tempdir().unwrap();
+        assert_eq!(EnrollmentStore::new(dir.path()).load().unwrap(), None);
+    }
+
+    /// An enrollment written before `ca_pem` existed still loads.
+    #[test]
+    fn an_enrollment_without_a_ca_still_loads() {
+        let dir = tempfile::tempdir().unwrap();
+        let store = EnrollmentStore::new(dir.path());
+        std::fs::create_dir_all(dir.path()).unwrap();
+        std::fs::write(
+            dir.path().join("enrollment.json"),
+            br#"{"host":"h","port":1,"token":"t"}"#,
+        )
+        .unwrap();
+        assert_eq!(store.load().unwrap().unwrap().ca_pem, None);
+    }
+
+    #[test]
+    #[cfg(unix)]
+    fn the_saved_file_is_owner_only() {
+        use std::os::unix::fs::PermissionsExt;
+        let dir = tempfile::tempdir().unwrap();
+        let store = EnrollmentStore::new(dir.path());
+        store
+            .save(&EnrolledServer {
+                host: "h".to_string(),
+                port: 1,
+                token: "t".to_string(),
+                ca_pem: None,
+            })
+            .unwrap();
+        let mode = std::fs::metadata(dir.path().join("enrollment.json"))
+            .unwrap()
+            .permissions()
+            .mode();
+        assert_eq!(mode & 0o777, 0o600);
+    }
+
+    #[test]
+    fn a_corrupt_file_is_named_in_the_error() {
+        let dir = tempfile::tempdir().unwrap();
+        std::fs::write(dir.path().join("enrollment.json"), b"not json").unwrap();
+        let err = EnrollmentStore::new(dir.path()).load().unwrap_err();
+        assert!(err.to_string().contains("enrollment.json"));
+    }
+
+    #[test]
+    fn a_non_numeric_port_is_named_in_the_error() {
+        let err = EnrolledServer::parse_link("aiapp://enroll?host=h&port=x&token=t").unwrap_err();
+        assert!(
+            err.contains("port"),
+            "error should name the offending field: {err}"
+        );
+    }
+}