feat(#2035): auto-discover dashboard-provisioned matrix accounts via token+homeserver sidecar

hive-matrix-mcp/src/accounts.rs

@@ -78,14 +78,13 @@ pub fn configured() -> anyhow::Result<Vec<AccountCfg>> {
         state_dir: paths::matrix_state_dir(),
         homeserver: None,
     };
-    let Some(raw) = std::env::var_os("HIVE_MATRIX_ACCOUNTS") else {
-        return Ok(vec![hive]);
-    };
-    let extras: Vec<AccountCfg> = serde_json::from_str(&raw.to_string_lossy())
-        .map_err(|e| anyhow::anyhow!("parse HIVE_MATRIX_ACCOUNTS as JSON array: {e}"))?;
-    let mut accounts = Vec::with_capacity(extras.len() + 1);
-    accounts.push(hive);
-    accounts.extend(extras);
+    let mut accounts = vec![hive];
+    if let Some(raw) = std::env::var_os("HIVE_MATRIX_ACCOUNTS") {
+        let extras: Vec<AccountCfg> = serde_json::from_str(&raw.to_string_lossy())
+            .map_err(|e| anyhow::anyhow!("parse HIVE_MATRIX_ACCOUNTS as JSON array: {e}"))?;
+        accounts.extend(extras);
+    }
+    // Reject duplicate names among the *configured* set (hive + extras).
     let mut seen = std::collections::HashSet::new();
     for a in &accounts {
         if !seen.insert(a.name.as_str()) {
@@ -95,9 +94,84 @@ pub fn configured() -> anyhow::Result<Vec<AccountCfg>> {
             );
         }
     }
+    // Append dashboard-provisioned accounts (a `matrix-token-<name>` file +
+    // its `matrix-account-<name>.json` homeserver sidecar) that aren't
+    // already declared in config, so an account logged in via the dashboard
+    // form works without a `matrixAccounts` edit + rebuild. Explicit config
+    // wins on name collision.
+    let configured: std::collections::HashSet<String> =
+        accounts.iter().map(|a| a.name.clone()).collect();
+    for disc in discover_token_accounts() {
+        if !configured.contains(&disc.name) {
+            accounts.push(disc);
+        }
+    }
     Ok(accounts)
 }
 
+/// Scan the agent state dir for extra matrix accounts provisioned via the
+/// dashboard login form: each is a `matrix-token-<name>` file plus a
+/// `matrix-account-<name>.json` sidecar carrying the homeserver. Returns one
+/// [`AccountCfg`] per discovered account that has BOTH files — a token
+/// without a sidecar is skipped, because the homeserver is then unknown and
+/// defaulting to the hive homeserver would be wrong for an external account.
+/// Best-effort: an unreadable dir or malformed sidecar yields fewer
+/// accounts, never an error — explicit `HIVE_MATRIX_ACCOUNTS` config stays
+/// authoritative.
+fn discover_token_accounts() -> Vec<AccountCfg> {
+    let token_path = paths::token_file();
+    let Some(state_dir) = token_path.parent() else {
+        return Vec::new();
+    };
+    let Ok(rd) = std::fs::read_dir(state_dir) else {
+        return Vec::new();
+    };
+    let mut out = Vec::new();
+    for entry in rd.flatten() {
+        let fname = entry.file_name();
+        let Some(fname) = fname.to_str() else {
+            continue;
+        };
+        // `matrix-token` (no suffix) is the hive account, handled separately;
+        // only `matrix-token-<name>` files are extra accounts.
+        let Some(name) = fname.strip_prefix("matrix-token-") else {
+            continue;
+        };
+        if name.is_empty() {
+            continue;
+        }
+        let sidecar = state_dir.join(format!("matrix-account-{name}.json"));
+        let Some(homeserver) = read_account_homeserver(&sidecar) else {
+            tracing::warn!(
+                account = name,
+                sidecar = %sidecar.display(),
+                "matrix: discovered token but no homeserver sidecar; skipping account \
+                 (re-login via the dashboard to write it)"
+            );
+            continue;
+        };
+        out.push(AccountCfg {
+            name: name.to_owned(),
+            token_file: entry.path(),
+            state_dir: state_dir.join(format!("matrix-sdk-state-{name}")),
+            homeserver: Some(homeserver),
+        });
+    }
+    out
+}
+
+/// Read `{"homeserver": "<url>"}` from a sidecar file. `None` when the file
+/// is missing, unreadable, not valid JSON, or the `homeserver` field is
+/// absent / empty.
+fn read_account_homeserver(path: &Path) -> Option<String> {
+    let raw = std::fs::read_to_string(path).ok()?;
+    let json: serde_json::Value = serde_json::from_str(&raw).ok()?;
+    json.get("homeserver")?
+        .as_str()
+        .filter(|s| !s.is_empty())
+        .map(ToOwned::to_owned)
+}
+
 /// Live status of one matrix account, as reported by [`Registry::list`]
 /// (the `list_accounts` daemon op). Only accounts that successfully
 /// restored a session appear, so `live` is always `true` today; the