feat: carry collaboration config in the protocol crate (lockstep) (#35)

Lockstep half of the daemon's "collaboration config on session.create"
(collaborative sessions P1a). CONTRIBUTING requires the Rust protocol crate
to move in the same change set as `packages/protocol/`.

- session.rs: CollaborationConfig + CollaborationRole, camelCase on the wire.
  `name` and `provider_id` are plain strings, not enums — the role taxonomy is
  data on the daemon side, so a new role like "security-reviewer" must not
  need a release of this crate to parse.
- client.rs: optional `collaboration` on ClientMessage::SessionCreate.
- session.rs: optional `collaboration` on SessionInfo.
- app.rs: the TUI's create path passes None — the collaborative create dialog
  is a later phase; this only keeps the frame builder compiling.

PROTOCOL_VERSION deliberately NOT bumped. It stays at 1 on both sides. The
change is purely additive (new optional fields), which CONTRIBUTING calls
additive-safe and lib.rs scopes the bump to "any breaking change". Bumping
only this crate would manufacture a version-mismatch warning on every connect
against a daemon that is otherwise fully compatible.

Verified: the existing wire_format camelCase test walks nested objects AND
arrays, so populating the SessionInfo fixture with a two-role collaboration
genuinely asserts `collaboration.roles[N].providerId` serializes camelCase —
it is not a vacuous fixture change.

cargo build + clippy + test green across the workspace (314 tests).

Author: saucam

crates/codeoid-protocol/src/client.rs

@@ -15,7 +15,7 @@
 use serde::{Deserialize, Serialize};
 use serde_json;
 
-use crate::session::SessionMode;
+use crate::session::{CollaborationConfig, SessionMode};
 
 /// Tagged union of every message a client can send the daemon.
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -30,6 +30,13 @@ pub enum ClientMessage {
         /// daemon fail-closes on unknown ids. Absent = daemon default.
         #[serde(default, skip_serializing_if = "Option::is_none")]
         provider_id: Option<String>,
+        /// Make this a collaborative session: one goal worked by several
+        /// role-children on their own backends. Absent = a normal session.
+        /// The daemon validates the semantics (provider registered, exactly
+        /// one orchestrator, claude-only orchestrator in v1) and answers
+        /// with a specific `invalid_request` error.
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        collaboration: Option<CollaborationConfig>,
     },
 
     #[serde(rename = "session.list", rename_all = "camelCase")]

crates/codeoid-protocol/src/lib.rs

@@ -52,8 +52,8 @@ pub use message::{
     ContentPart, IdentityType, MessageIdentity, MessageRole, SessionMessage, SessionMessageDelta,
 };
 pub use session::{
-    ForkedFrom, SessionInfo, SessionMode, SessionStatus, SessionUsage, SessionWorktree, Subagent,
-    TurnUsage,
+    CollaborationConfig, CollaborationRole, ForkedFrom, SessionInfo, SessionMode, SessionStatus,
+    SessionUsage, SessionWorktree, Subagent, TurnUsage,
 };
 pub use tool::{CancelReason, ConfirmedBy, ToolInfo, ToolPhase, ToolState};
 

crates/codeoid-protocol/src/session.rs

@@ -94,6 +94,13 @@ pub struct SessionInfo {
     /// "⎇ <branch>" tag in the session title.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub worktree: Option<SessionWorktree>,
+
+    /// Collaboration this session orchestrates — goal + role→backend
+    /// bindings — when it was created with the Collaborative toggle.
+    /// Absent = a normal session. Persisted daemon-side, so it survives a
+    /// restart the way `role`/`provider_id` already do.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub collaboration: Option<CollaborationConfig>,
 }
 
 /// Where a forked session came from — the parent id, the parent's name at
@@ -118,6 +125,45 @@ pub struct SessionWorktree {
     pub created_by_codeoid: bool,
 }
 
+/// One role in a collaborative session — a `{backend, model}` binding chosen
+/// per purpose.
+///
+/// `name` is a free-form string, not an enum: the role taxonomy is data, so
+/// the daemon can add "security-reviewer" as a config change and this crate
+/// keeps parsing it without a release.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct CollaborationRole {
+    pub name: String,
+    /// Backend this role's children run on. The daemon fail-closes on an id
+    /// it does not have registered.
+    pub provider_id: String,
+    /// Model within that backend. `None` = the backend's own default.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub model: Option<String>,
+    /// How many children to fan out for this role. `None` = 1; >1 is what
+    /// makes a review panel a panel.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub count: Option<u32>,
+    /// What this role is for; surfaced in the child's brief.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub purpose: Option<String>,
+}
+
+/// Collaborative-session config: one goal worked by several role-children on
+/// possibly different backends. Sent on `session.create` and echoed back on
+/// [`SessionInfo`].
+///
+/// Exactly one role must be named `orchestrator`, and in v1 it must sit on
+/// the claude backend. The daemon enforces both and answers with a specific
+/// error, so this crate carries only the shape.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct CollaborationConfig {
+    pub goal: String,
+    pub roles: Vec<CollaborationRole>,
+}
+
 /// Rotation telemetry — how many times the backing Claude Code session has
 /// been rolled over to avoid context compaction.
 #[derive(Debug, Clone, Serialize, Deserialize)]

crates/codeoid-protocol/tests/wire_format.rs

@@ -118,6 +118,25 @@ fn sample_session_info() -> SessionInfo {
             branch: "codeoid/fix-a1b2".into(),
             created_by_codeoid: true,
         }),
+        collaboration: Some(codeoid_protocol::CollaborationConfig {
+            goal: "Add rate limiting to the public API".into(),
+            roles: vec![
+                codeoid_protocol::CollaborationRole {
+                    name: "orchestrator".into(),
+                    provider_id: "claude".into(),
+                    model: None,
+                    count: None,
+                    purpose: None,
+                },
+                codeoid_protocol::CollaborationRole {
+                    name: "review".into(),
+                    provider_id: "gemini".into(),
+                    model: Some("gemini-2.5-pro".into()),
+                    count: Some(3),
+                    purpose: Some("independent critique".into()),
+                },
+            ],
+        }),
     }
 }
 
@@ -179,6 +198,7 @@ fn client_messages_are_camel_case_on_wire() {
                 name: "n".into(),
                 workdir: "/".into(),
                 provider_id: Some("pi".into()),
+                collaboration: None,
             },
         ),
         ("SessionList", ClientMessage::SessionList { id: "1".into() }),

crates/codeoid-tui/src/app.rs

@@ -2515,6 +2515,9 @@ fn session_create_message(
         name,
         workdir,
         provider_id,
+        // The TUI has no collaborative-create surface yet (that lands with
+        // the extended create dialog); omitted means a normal session.
+        collaboration: None,
     }
 }
 
@@ -2649,6 +2652,7 @@ mod tests {
             provider_id: None,
             forked_from: None,
             worktree: None,
+            collaboration: None,
         });
         state
     }

crates/codeoid-tui/src/state/mod.rs

@@ -1155,6 +1155,7 @@ mod tests {
             provider_id: None,
             forked_from: None,
             worktree: None,
+            collaboration: None,
         }
     }
 

crates/codeoid-tui/src/state/sessions.rs

@@ -130,6 +130,7 @@ mod tests {
             provider_id: None,
             forked_from: None,
             worktree: None,
+            collaboration: None,
         }
     }
 

crates/codeoid-tui/src/ui/approval.rs

@@ -292,6 +292,7 @@ mod tests {
             provider_id: None,
             forked_from: None,
             worktree: None,
+            collaboration: None,
         });
         let mut m = msg(
             MessageRole::ToolCall,

crates/codeoid-tui/src/ui/scrollback.rs

@@ -643,6 +643,7 @@ mod tests {
             provider_id: None,
             forked_from: None,
             worktree: None,
+            collaboration: None,
         }
     }
 

crates/codeoid-tui/src/ui/worker.rs

@@ -440,6 +440,7 @@ mod tests {
             provider_id: None,
             forked_from: None,
             worktree: None,
+            collaboration: None,
         });
         state.provider_commands.insert(
             "s1".into(),