feat(tools): create_project_from_template

Generates a new repo from mathias/template-go-web via Gitea's generate
API, then substitutes __PROJECT_NAME__ and __MODULE_PATH__ placeholders
in six known files (best-effort, partial failure surfaced in result).

Validates name regex, allowlist, template flag, and destination
non-existence before generating. Adds Template field to gitea.Repo.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/gitea/repos.go

@@ -15,6 +15,7 @@ type Repo struct {
 	Private       bool   `json:"private"`
 	CloneURL      string `json:"clone_url"`
 	HTMLURL       string `json:"html_url"`
+	Template      bool   `json:"template"`
 }
 
 func (c *Client) ListRepos(ctx context.Context, owner string, page, limit int) ([]Repo, error) {

internal/gitea/templates.go

@@ -0,0 +1,72 @@
+package gitea
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// GenerateFromTemplateArgs is the request body for POST /repos/{owner}/{repo}/generate.
+type GenerateFromTemplateArgs struct {
+	Owner         string `json:"owner"`
+	Name          string `json:"name"`
+	Description   string `json:"description,omitempty"`
+	Private       bool   `json:"private"`
+	DefaultBranch string `json:"default_branch,omitempty"`
+	GitContent    bool   `json:"git_content"` // include all template files
+}
+
+// GenerateFromTemplate creates a new repository from a template via POST /repos/{tmplOwner}/{tmplName}/generate.
+func (c *Client) GenerateFromTemplate(ctx context.Context, tmplOwner, tmplName string, args GenerateFromTemplateArgs) (*Repo, error) {
+	p := fmt.Sprintf("/api/v1/repos/%s/%s/generate", tmplOwner, tmplName)
+	payload, err := json.Marshal(args)
+	if err != nil {
+		return nil, err
+	}
+	body, status, err := c.PostJSON(ctx, p, payload)
+	if err != nil {
+		return nil, err
+	}
+	if err := MapStatus(status, body); err != nil {
+		return nil, err
+	}
+	var r Repo
+	if err := json.Unmarshal(body, &r); err != nil {
+		return nil, err
+	}
+	return &r, nil
+}
+
+// SubstituteFile reads a file from the given branch, applies string replacements,
+// and writes it back if any changes were made. Best-effort — returns a wrapped error
+// that includes the file path.
+func (c *Client) SubstituteFile(ctx context.Context, owner, repo, branch, path string, replacements map[string]string) error {
+	fc, err := c.GetFileContents(ctx, owner, repo, path, branch)
+	if err != nil {
+		return fmt.Errorf("read %s: %w", path, err)
+	}
+	decoded, err := base64.StdEncoding.DecodeString(fc.Content)
+	if err != nil {
+		return fmt.Errorf("decode %s: %w", path, err)
+	}
+	content := string(decoded)
+	for k, v := range replacements {
+		content = strings.ReplaceAll(content, k, v)
+	}
+	if content == string(decoded) {
+		return nil // no changes, skip write
+	}
+	encoded := base64.StdEncoding.EncodeToString([]byte(content))
+	_, err = c.UpsertFile(ctx, owner, repo, path, UpsertFileArgs{
+		Branch:  branch,
+		Content: encoded,
+		Message: "Apply template substitutions",
+		Sha:     fc.Sha,
+	})
+	if err != nil {
+		return fmt.Errorf("write %s: %w", path, err)
+	}
+	return nil
+}

internal/gitea/templates_test.go

@@ -0,0 +1,156 @@
+package gitea_test
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+
+	"gitea.d-ma.be/mathias/gitea-mcp/internal/gitea"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGenerateFromTemplate(t *testing.T) {
+	var capturedBody []byte
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, "/api/v1/repos/mathias/template-go-web/generate", r.URL.Path)
+		assert.Equal(t, http.MethodPost, r.Method)
+		var err error
+		capturedBody, err = io.ReadAll(r.Body)
+		require.NoError(t, err)
+		w.WriteHeader(http.StatusCreated)
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"name":"new-svc",
+			"full_name":"mathias/new-svc",
+			"default_branch":"main",
+			"description":"A new service",
+			"private":true,
+			"clone_url":"http://gitea.example.com/mathias/new-svc.git",
+			"html_url":"http://gitea.example.com/mathias/new-svc",
+			"template":false
+		}`))
+	}))
+	defer srv.Close()
+
+	c := gitea.NewClient(srv.URL, "tok")
+	repo, err := c.GenerateFromTemplate(context.Background(), "mathias", "template-go-web", gitea.GenerateFromTemplateArgs{
+		Owner:       "mathias",
+		Name:        "new-svc",
+		Description: "A new service",
+		Private:     true,
+		GitContent:  true,
+	})
+	require.NoError(t, err)
+
+	// Verify the captured POST body contains the expected fields.
+	var payload map[string]any
+	require.NoError(t, json.Unmarshal(capturedBody, &payload))
+	assert.Equal(t, "mathias", payload["owner"])
+	assert.Equal(t, "new-svc", payload["name"])
+	assert.Equal(t, "A new service", payload["description"])
+	assert.Equal(t, true, payload["private"])
+	assert.Equal(t, true, payload["git_content"])
+
+	// Verify the decoded repo fields.
+	assert.Equal(t, "new-svc", repo.Name)
+	assert.Equal(t, "mathias/new-svc", repo.FullName)
+	assert.Equal(t, "main", repo.DefaultBranch)
+	assert.Equal(t, "A new service", repo.Description)
+	assert.True(t, repo.Private)
+	assert.Equal(t, "http://gitea.example.com/mathias/new-svc.git", repo.CloneURL)
+	assert.Equal(t, "http://gitea.example.com/mathias/new-svc", repo.HTMLURL)
+}
+
+func TestSubstituteFileApplies(t *testing.T) {
+	originalContent := "module __MODULE_PATH__\n\ngo 1.22\n"
+	encoded := base64.StdEncoding.EncodeToString([]byte(originalContent))
+
+	var capturedPutBody []byte
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			assert.Equal(t, "/api/v1/repos/mathias/new-svc/contents/go.mod", r.URL.Path)
+			assert.Equal(t, "main", r.URL.Query().Get("ref"))
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{"path":"go.mod","sha":"abc123","size":30,"content":"` + encoded + `","encoding":"base64"}`))
+		case http.MethodPut:
+			assert.Equal(t, "/api/v1/repos/mathias/new-svc/contents/go.mod", r.URL.Path)
+			var err error
+			capturedPutBody, err = io.ReadAll(r.Body)
+			require.NoError(t, err)
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`{"content":{"path":"go.mod","sha":"newsha","html_url":""},"commit":{"sha":"commitsha","html_url":""}}`))
+		default:
+			t.Errorf("unexpected method %s", r.Method)
+			w.WriteHeader(http.StatusMethodNotAllowed)
+		}
+	}))
+	defer srv.Close()
+
+	c := gitea.NewClient(srv.URL, "tok")
+	err := c.SubstituteFile(context.Background(), "mathias", "new-svc", "main", "go.mod", map[string]string{
+		"__MODULE_PATH__": "gitea.d-ma.be/mathias/new-svc",
+	})
+	require.NoError(t, err)
+
+	// Verify the PUT body contains the substituted content.
+	require.NotNil(t, capturedPutBody, "PUT should have been called")
+	var payload map[string]string
+	require.NoError(t, json.Unmarshal(capturedPutBody, &payload))
+
+	decoded, err := base64.StdEncoding.DecodeString(payload["content"])
+	require.NoError(t, err)
+	assert.Contains(t, string(decoded), "gitea.d-ma.be/mathias/new-svc")
+	assert.NotContains(t, string(decoded), "__MODULE_PATH__")
+	assert.Equal(t, "abc123", payload["sha"])
+	assert.Equal(t, "Apply template substitutions", payload["message"])
+}
+
+func TestSubstituteFileNoChangeSkipsWrite(t *testing.T) {
+	originalContent := "module gitea.d-ma.be/mathias/existing\n\ngo 1.22\n"
+	encoded := base64.StdEncoding.EncodeToString([]byte(originalContent))
+
+	var putCount atomic.Int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{"path":"go.mod","sha":"abc123","size":40,"content":"` + encoded + `","encoding":"base64"}`))
+		case http.MethodPut:
+			putCount.Add(1)
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`{"content":{"path":"go.mod","sha":"newsha","html_url":""},"commit":{"sha":"c","html_url":""}}`))
+		}
+	}))
+	defer srv.Close()
+
+	c := gitea.NewClient(srv.URL, "tok")
+	// Replacements that don't match anything in the content.
+	err := c.SubstituteFile(context.Background(), "mathias", "new-svc", "main", "go.mod", map[string]string{
+		"__MODULE_PATH__": "gitea.d-ma.be/mathias/new-svc",
+	})
+	require.NoError(t, err)
+	assert.Equal(t, int32(0), putCount.Load(), "PUT should not be called when content is unchanged")
+}
+
+func TestSubstituteFileReadError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		_, _ = w.Write([]byte(`{"message":"file not found"}`))
+	}))
+	defer srv.Close()
+
+	c := gitea.NewClient(srv.URL, "tok")
+	err := c.SubstituteFile(context.Background(), "mathias", "new-svc", "main", "go.mod", map[string]string{
+		"__MODULE_PATH__": "gitea.d-ma.be/mathias/new-svc",
+	})
+	require.Error(t, err)
+	assert.True(t, errors.Is(err, gitea.ErrNotFound), "error should wrap ErrNotFound, got: %v", err)
+}