agent surface: create_repo through hive-c0re (#1787)

Closes the #1787 loop — the sanctioned create path now that agents
can't create repos directly. Adds:

- wire: Request::CreateRepo{repo} + Response::RepoCreated{full_name,
  clone_url} (hive-sh4re).
- agent_server: dispatch_shared arm + handle_create_repo — validates the
  repo name, then forge::create_agent_repo (org-owned repo, agent=write
  collaborator, operator-team branch protection). Returns the full name
  + clone url so the agent can git clone immediately.
- MCP: create_repo tool + CreateRepoArgs in the harness.
- a new opt-in ToolGroup::Forge (=[create_repo]) so the operator
  controls which agents can spin up repos (least privilege).

Workspace clippy -D warnings, cargo test, nix fmt all green.

hive-ag3nt/src/mcp.rs

@@ -59,6 +59,11 @@ pub enum SocketReply {
         hive_name: Option<String>,
         swarm_name: Option<String>,
     },
+    /// `create_repo` result — the new repo's full name + clone URL.
+    RepoCreated {
+        full_name: String,
+        clone_url: String,
+    },
 }
 
 impl From<hive_sh4re::Response> for SocketReply {
@@ -100,6 +105,13 @@ impl From<hive_sh4re::Response> for SocketReply {
                 hive_name,
                 swarm_name,
             },
+            hive_sh4re::Response::RepoCreated {
+                full_name,
+                clone_url,
+            } => Self::RepoCreated {
+                full_name,
+                clone_url,
+            },
         }
     }
 }
@@ -910,6 +922,35 @@ impl AgentServer {
         .await
     }
 
+    #[tool(
+        description = "Create a git repo through hive-c0re. You CANNOT create repos with your \
+        own forge token (creation is disabled) — this is the only path. The repo is created in \
+        the c0re-owned `agents` org, you're added as a write collaborator (not owner), and the \
+        default branch gets branch protection so merges require an operator-team approval — you \
+        cannot merge your own PRs. `repo` is a single name segment (letters, digits, `-`, `_`, \
+        `.`). Returns the new repo's full name + clone URL; clone it over \
+        `http://localhost:3000/agents/<repo>.git` and push/open PRs as normal."
+    )]
+    async fn create_repo(&self, Parameters(args): Parameters<CreateRepoArgs>) -> String {
+        let log = format!("{args:?}");
+        run_tool_envelope("create_repo", log, async move {
+            let (resp, retries) = self
+                .dispatch(hive_sh4re::Request::CreateRepo { repo: args.repo })
+                .await;
+            let s = match resp {
+                Ok(SocketReply::RepoCreated {
+                    full_name,
+                    clone_url,
+                }) => format!("created repo {full_name} — clone: {clone_url}"),
+                Ok(SocketReply::Err(m)) => format!("create_repo failed: {m}"),
+                Ok(other) => format!("create_repo unexpected response: {other:?}"),
+                Err(e) => format!("create_repo transport error: {e:#}"),
+            };
+            annotate_retries(s, retries)
+        })
+        .await
+    }
+
     #[tool(
         description = "Schedule a reminder that lands in this agent's own inbox at a future \
         time (sender will appear as `reminder`). Use for self-paced follow-ups: 'check task \
@@ -1505,6 +1546,13 @@ pub struct SetStatusArgs {
     pub text: String,
 }
 
+#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
+pub struct CreateRepoArgs {
+    /// Repo name — a single segment of letters, digits, `-`, `_`, `.`
+    /// (no leading `-`/`.`). The repo is created as `agents/<repo>`.
+    pub repo: String,
+}
+
 #[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
 pub struct GetAgentMetaArgs {
     /// Logical name of the agent to query (e.g. `"iris"`, `"manager"`).