feat(routing): project_create MCP tool — gitea-first new-project pipeline (#10)

Adds the project_create tool to the routing pod that automates the
"new project" bootstrap end-to-end from claude.ai. Gitea-first
architecture: GitHub receives the repo only via push-mirror, never
via a direct GitHub API call from this server.

Four sequential calls to the gitea-mcp server (configured via
GITEA_MCP_URL):

  1. create_project_from_template — Gitea repo from
     template-go-{agent,web} per the 'stack' arg
  2. repo_mirror_push (action=add) — push-mirror to
     github.com/<GITHUB_OWNER>/<name>.git, interval 8h, sync_on_commit
  3. file_write_branch — k3s/staging/<name>/namespace.yaml committed
     on a staging/<name> branch in the infra repo
  4. issue_create — experiment brief (hypothesis + description + stack
     + provisioning log) on the new repo, returns the issue_url

Returns gitea_url, github_url, issue_url, next_steps. The next_steps
string is the exact shell sequence the operator runs locally to
clone, scaffold via local-dev 'task new-project', and push.

Idempotency: create_project_from_template + repo_mirror_push +
file_write_branch all return JSON-RPC code -32003 (Conflict) when
their target already exists; the orchestrator swallows the conflict
and continues. Re-running on an existing repo restates the brief in
a fresh issue.

Error handling: on any non-conflict downstream failure the response
returns {reached: ["<step>",...], failed_step: "<step>"} alongside
a JSON-RPC error. No rollback — partial state stays so the operator
can resume manually.

New env vars (all optional except GITEA_MCP_URL):
  GITEA_MCP_URL    enables the tool
  GITEA_MCP_TOKEN  bearer auth for gitea-mcp
  GITEA_OWNER      default mathias
  GITHUB_OWNER     default mathiasb
  INFRA_REPO       default infra
  GITHUB_PAT       repo scope, used as mirror remote_password; never logged

Without GITEA_MCP_URL set, the tool is not registered and the
routing pod starts normally (degrades open).

internal/mcpclient/: new minimal JSON-RPC tools/call client with
bearer auth, used by project_create. Unwraps MCP's
content[0].text envelope and surfaces typed errors via mcpclient.Error.

Tests: table-driven against an httptest fake gitea-mcp covering happy
path (4-step success + correct PATCH-style arg shapes), idempotent
repo-exists, mirror failure (partial-success response with reached=
[create_repo] + failed_step=mirror), infra-commit failure (reached up
to mirror + failed_step=infra_commit), and validation errors.

Closes #10

internal/mcpclient/client.go

@@ -0,0 +1,135 @@
+// Package mcpclient is a minimal JSON-RPC over HTTP client for talking to
+// MCP servers from inside hyperguild components. It only implements
+// `tools/call` because that's all consumer skills need today.
+package mcpclient
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+// Client calls an MCP server over Streamable HTTP / JSON-RPC.
+type Client struct {
+	url    string
+	token  string
+	http   *http.Client
+}
+
+// New returns a Client. token may be empty for unauthenticated servers.
+func New(url, token string) *Client {
+	return &Client{
+		url:   url,
+		token: token,
+		http:  &http.Client{Timeout: 60 * time.Second},
+	}
+}
+
+// WithHTTPClient overrides the underlying HTTP client (test injection).
+func (c *Client) WithHTTPClient(h *http.Client) *Client {
+	c.http = h
+	return c
+}
+
+type rpcRequest struct {
+	JSONRPC string         `json:"jsonrpc"`
+	ID      int            `json:"id"`
+	Method  string         `json:"method"`
+	Params  map[string]any `json:"params"`
+}
+
+type rpcError struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+type rpcResponse struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      int             `json:"id"`
+	Result  json.RawMessage `json:"result,omitempty"`
+	Error   *rpcError       `json:"error,omitempty"`
+}
+
+// Error is returned when the remote MCP server signals a typed failure.
+// Code follows JSON-RPC conventions; see gitea-mcp internal/mcp/jsonrpc.go
+// for the codes the server uses (e.g. -32002 NotFound, -32003 Conflict).
+type Error struct {
+	Code    int
+	Message string
+}
+
+func (e *Error) Error() string { return fmt.Sprintf("mcp error %d: %s", e.Code, e.Message) }
+
+// CallTool issues `tools/call`. result is JSON-unmarshalled from the
+// server's content[0].text field; pass nil to discard.
+func (c *Client) CallTool(ctx context.Context, name string, args any, result any) error {
+	body, err := json.Marshal(rpcRequest{
+		JSONRPC: "2.0",
+		ID:      1,
+		Method:  "tools/call",
+		Params: map[string]any{
+			"name":      name,
+			"arguments": args,
+		},
+	})
+	if err != nil {
+		return fmt.Errorf("marshal request: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.url, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("new request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	if c.token != "" {
+		req.Header.Set("Authorization", "Bearer "+c.token)
+	}
+
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return fmt.Errorf("http: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	raw, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("read body: %w", err)
+	}
+	if resp.StatusCode >= 400 {
+		return fmt.Errorf("mcp http %d: %s", resp.StatusCode, string(raw))
+	}
+
+	var rpc rpcResponse
+	if err := json.Unmarshal(raw, &rpc); err != nil {
+		return fmt.Errorf("decode response: %w (body=%s)", err, string(raw))
+	}
+	if rpc.Error != nil {
+		return &Error{Code: rpc.Error.Code, Message: rpc.Error.Message}
+	}
+
+	if result == nil {
+		return nil
+	}
+
+	// MCP success result shape: { content: [{type:"text", text:"<json>"}] }
+	var wrap struct {
+		Content []struct {
+			Type string `json:"type"`
+			Text string `json:"text"`
+		} `json:"content"`
+	}
+	if err := json.Unmarshal(rpc.Result, &wrap); err != nil {
+		return fmt.Errorf("decode wrap: %w (result=%s)", err, string(rpc.Result))
+	}
+	if len(wrap.Content) == 0 {
+		return fmt.Errorf("empty content in tool response")
+	}
+	if err := json.Unmarshal([]byte(wrap.Content[0].Text), result); err != nil {
+		return fmt.Errorf("decode tool result text: %w (text=%s)", err, wrap.Content[0].Text)
+	}
+	return nil
+}

internal/mcpclient/client_test.go

@@ -0,0 +1,82 @@
+package mcpclient_test
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/mathiasbq/supervisor/internal/mcpclient"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCallTool_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, http.MethodPost, r.Method)
+		assert.Equal(t, "Bearer tok", r.Header.Get("Authorization"))
+		b, _ := io.ReadAll(r.Body)
+		var got map[string]any
+		_ = json.Unmarshal(b, &got)
+		assert.Equal(t, "tools/call", got["method"])
+		params := got["params"].(map[string]any)
+		assert.Equal(t, "x_y", params["name"])
+
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"jsonrpc":"2.0","id":1,"result":{"content":[{"type":"text","text":"{\"ok\":true,\"n\":7}"}]}}`))
+	}))
+	defer srv.Close()
+
+	c := mcpclient.New(srv.URL, "tok")
+	var out struct {
+		OK bool `json:"ok"`
+		N  int  `json:"n"`
+	}
+	err := c.CallTool(context.Background(), "x_y", map[string]any{"a": 1}, &out)
+	require.NoError(t, err)
+	assert.True(t, out.OK)
+	assert.Equal(t, 7, out.N)
+}
+
+func TestCallTool_RPCError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"jsonrpc":"2.0","id":1,"error":{"code":-32003,"message":"already exists"}}`))
+	}))
+	defer srv.Close()
+
+	c := mcpclient.New(srv.URL, "")
+	err := c.CallTool(context.Background(), "x", nil, nil)
+	require.Error(t, err)
+	var me *mcpclient.Error
+	require.True(t, errors.As(err, &me))
+	assert.Equal(t, -32003, me.Code)
+	assert.Contains(t, me.Message, "already exists")
+}
+
+func TestCallTool_HTTPError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusUnauthorized)
+		_, _ = w.Write([]byte(`unauthorized`))
+	}))
+	defer srv.Close()
+
+	c := mcpclient.New(srv.URL, "")
+	err := c.CallTool(context.Background(), "x", nil, nil)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "401")
+}
+
+func TestCallTool_NilResult(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"jsonrpc":"2.0","id":1,"result":{"content":[{"type":"text","text":"{}"}]}}`))
+	}))
+	defer srv.Close()
+
+	c := mcpclient.New(srv.URL, "")
+	require.NoError(t, c.CallTool(context.Background(), "x", nil, nil))
+}