mr-668: CLI omnigraph graphs list/create (PR 8/10)

PR 8 of the MR-668 multi-graph server work. CLI parity for the
v0.7.0 management surface: operators can now manage graphs from
the command line against a running multi-graph server.

  omnigraph graphs list --target dev --json
  omnigraph graphs create \
    --target dev \
    --graph-id beta \
    --graph-uri /data/beta.omni \
    --schema schema.pg

DELETE is intentionally absent — server-side DELETE was deferred from
v0.7.0 scope, and shipping a client subcommand for a server endpoint
that doesn't exist would be dead vocabulary. The help output, the
subcommand enum, and the test that pins it (`graphs_subcommand_help_
lists_list_and_create`) all agree.

CLI architecture (modeled on `BranchCommand`):
  - New `Command::Graphs { command: GraphsCommand }` top-level variant.
  - `GraphsCommand { List, Create }` enum.
  - List: GET `<base>/graphs`. Stdout is `<graph_id>\t<uri>` per line,
    or JSON via `--json`.
  - Create: reads `--schema <path>` from local disk, inlines as
    `schema: { source: <file> }` in the POST body (nested per
    MR-668 decision 7). Optional `--policy-file <path>` becomes
    `policy: { file: <path> }`. Returns 201 → "created graph X at Y"
    or JSON via `--json`.
  - Both subcommands reject local URI targets with a clear
    "remote multi-graph server URL" error.

New API type imports in the CLI: `GraphCreateRequest`,
`GraphCreateResponse`, `GraphListResponse`, `GraphSchemaSpec`,
`GraphPolicySpec` — all from `omnigraph-server::api`.

Tests:
  - cli.rs (4 new, non-network):
      * `graphs_subcommand_help_lists_list_and_create` — pins the
        deferral of `delete` (catches scope creep).
      * `graphs_list_against_local_uri_errors_with_remote_only_message`
      * `graphs_create_against_local_uri_errors_with_remote_only_message`
      * `graphs_create_with_missing_schema_file_errors` — pins the
        IO context in the schema-read error path.
  - system_remote.rs (1 new, `#[ignore]` like its peers):
      * `graphs_list_and_create_against_multi_graph_server` — spawns a
        multi-mode server, calls `graphs list` (sees `alpha`),
        `graphs create` (adds `beta`), `graphs list` again (sees both),
        and confirms the new graph is reachable via its cluster route.

CLI suite: 62 tests green (58 existing + 4 new). The new ignored
end-to-end test runs locally with `cargo test --ignored`.

LOC: +159 main.rs (enum + handlers), +88 cli.rs (unit tests),
+131 system_remote.rs (integration test).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/omnigraph-cli/tests/system_remote.rs

@@ -888,3 +888,134 @@ query insert_person($name: String, $age: I32) {
     assert_eq!(verify["row_count"], 1);
     assert_eq!(verify["rows"][0]["p.name"], "PolicyRemote");
 }
+
+// ─── MR-668 PR 8 — omnigraph graphs end-to-end ──────────────────────────────
+
+/// Multi-graph server + CLI `omnigraph graphs list` / `create` end-to-end.
+///
+/// Steps:
+///   1. Init a graph `alpha` on disk and write an `omnigraph.yaml`
+///      whose `graphs:` map references it.
+///   2. Spawn the server with `--config <yaml>`.
+///   3. `omnigraph graphs list` — expect to see `alpha`.
+///   4. `omnigraph graphs create --graph-id beta --schema ...` —
+///      expect 201 and stdout reflecting the new graph.
+///   5. `omnigraph graphs list` again — expect both `alpha` and `beta`.
+///
+/// Ignored by default — spawning servers needs loopback socket
+/// permissions some sandboxes lack.
+#[test]
+#[ignore = "requires loopback socket permissions in sandboxed runners"]
+fn graphs_list_and_create_against_multi_graph_server() {
+    let cfg_dir = tempfile::tempdir().unwrap();
+    let schema_path = fixture("test.pg");
+
+    // Init `alpha` on disk.
+    let alpha_uri = cfg_dir.path().join("alpha.omni");
+    tokio::runtime::Runtime::new().unwrap().block_on(async {
+        Omnigraph::init(
+            alpha_uri.to_str().unwrap(),
+            &fs::read_to_string(&schema_path).unwrap(),
+        )
+        .await
+        .unwrap();
+    });
+
+    // Server config with `graphs:` map and no `server.graph` selector
+    // — multi mode (rule 4 of the inference matrix).
+    let server_config_path = cfg_dir.path().join("omnigraph.yaml");
+    fs::write(
+        &server_config_path,
+        format!(
+            "\
+graphs:
+  alpha:
+    uri: {}
+",
+            yaml_string(&alpha_uri.to_string_lossy())
+        ),
+    )
+    .unwrap();
+
+    let server = spawn_server_with_config(&server_config_path);
+
+    // Client config — the CLI's `--target dev` resolves to `server.base_url`.
+    let client_config_path = cfg_dir.path().join("client.yaml");
+    fs::write(
+        &client_config_path,
+        format!(
+            "\
+graphs:
+  dev:
+    uri: {}
+cli:
+  graph: dev
+",
+            yaml_string(&server.base_url)
+        ),
+    )
+    .unwrap();
+
+    // 1. `graphs list` lists `alpha`.
+    let payload = parse_stdout_json(&output_success(
+        cli()
+            .arg("graphs")
+            .arg("list")
+            .arg("--config")
+            .arg(&client_config_path)
+            .arg("--json"),
+    ));
+    let initial_ids: Vec<&str> = payload["graphs"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|g| g["graph_id"].as_str().unwrap())
+        .collect();
+    assert_eq!(initial_ids, vec!["alpha"]);
+
+    // 2. `graphs create` adds `beta`.
+    let beta_uri = cfg_dir.path().join("beta.omni");
+    let created = parse_stdout_json(&output_success(
+        cli()
+            .arg("graphs")
+            .arg("create")
+            .arg("--config")
+            .arg(&client_config_path)
+            .arg("--graph-id")
+            .arg("beta")
+            .arg("--graph-uri")
+            .arg(beta_uri.to_str().unwrap())
+            .arg("--schema")
+            .arg(&schema_path)
+            .arg("--json"),
+    ));
+    assert_eq!(created["graph_id"], "beta");
+
+    // 3. `graphs list` now lists both, sorted alphabetically.
+    let payload = parse_stdout_json(&output_success(
+        cli()
+            .arg("graphs")
+            .arg("list")
+            .arg("--config")
+            .arg(&client_config_path)
+            .arg("--json"),
+    ));
+    let final_ids: Vec<&str> = payload["graphs"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|g| g["graph_id"].as_str().unwrap())
+        .collect();
+    assert_eq!(final_ids, vec!["alpha", "beta"]);
+
+    // 4. The new graph is reachable via its cluster snapshot route.
+    let client = Client::new();
+    let snap_status = client
+        .get(format!("{}/graphs/beta/snapshot?branch=main", server.base_url))
+        .send()
+        .unwrap()
+        .status();
+    assert_eq!(snap_status.as_u16(), 200);
+
+    drop(server);
+}