gitea: let an agent put a commit on a branch of its own, and read history, compares, reviews, directories and code (issue 375)

An agent could not get a finished change onto the forge without someone
pushing by hand, so the branch / pull request / approval rule could not be
followed. A Go bundle serves gitea_commit, held to gitea_api's rule (never the
default branch, never a protected one), and the summarised reads agents
otherwise made through gitea_api as raw JSON.

modules/gitea/cmd/forge/commit.go

@@ -0,0 +1,332 @@
+package main
+
+import (
+	"context"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+	"unicode/utf8"
+)
+
+// gitea_commit (novox/hq issue 375): one commit on a branch of its own, so an agent follows the branch / pull
+// request / approval rule without anyone pushing by hand. By the rule gitea_api already enforces for a file
+// written (novox/hq ADR 0266): never the repository's default branch, never a branch a protection rule names.
+// Nothing about merging changes — that still needs a review at the head and both required checks green
+// (gitea_merge_pull_request).
+
+// FileChange is one file of a commit: its new content, as text or base64, or its deletion.
+type FileChange struct {
+	Path          string
+	Content       *string
+	ContentBase64 *string
+	Delete        bool
+}
+
+// CommitAsk is one gitea_commit call.
+type CommitAsk struct {
+	Owner, Repo string
+	Branch      string
+	Base        string // the branch or commit a new branch starts from; the default branch when empty
+	Message     string
+	Files       []FileChange
+	Patch       string // a unified diff, as git diff writes it, instead of Files
+}
+
+// Committed is what gitea_commit made.
+type Committed struct {
+	Repository string          `json:"repository"`
+	Branch     string          `json:"branch"`
+	Created    bool            `json:"created"`
+	Base       string          `json:"base,omitempty"`
+	Parent     string          `json:"parent"`
+	Commit     string          `json:"commit"`
+	Files      []CommittedFile `json:"files,omitempty"`
+	Said       []string        `json:"said"`
+}
+
+// CommittedFile is one file the commit changed, and how.
+type CommittedFile struct {
+	Path      string `json:"path"`
+	Operation string `json:"operation"`
+}
+
+// maxFiles is the most files one commit carries.
+const maxFiles = 200
+
+// readCommitAsk reads the tool's arguments.
+func readCommitAsk(args map[string]any) (CommitAsk, error) {
+	a := CommitAsk{Owner: text(args, "owner"), Repo: text(args, "repo"), Branch: text(args, "branch"),
+		Base: text(args, "base"), Message: strings.TrimSpace(raw(args, "message"))}
+	a.Patch = raw(args, "patch")
+	if a.Branch == "" {
+		return a, refuse("branch is required: the branch the commit goes on, a branch of its own (created from base when absent). Nothing was sent")
+	}
+	if a.Message == "" {
+		return a, refuse("message is required: the commit's message. Nothing was sent")
+	}
+	files, given := args["files"]
+	if given && files != nil {
+		list, ok := files.([]any)
+		if !ok {
+			return a, refuse("files is a list of {path, content | content_base64 | delete: true}. Nothing was sent")
+		}
+		for i, item := range list {
+			m, ok := item.(map[string]any)
+			if !ok {
+				return a, refuse("files[%d] is not an object {path, content | content_base64 | delete: true}. Nothing was sent", i)
+			}
+			fc := FileChange{Path: text(m, "path")}
+			if v, ok := m["content"]; ok && v != nil {
+				s, ok := v.(string)
+				if !ok {
+					return a, refuse("files[%d].content is text. Nothing was sent", i)
+				}
+				fc.Content = &s
+			}
+			if v, ok := m["content_base64"]; ok && v != nil {
+				s, ok := v.(string)
+				if !ok {
+					return a, refuse("files[%d].content_base64 is text. Nothing was sent", i)
+				}
+				fc.ContentBase64 = &s
+			}
+			if v, ok := m["delete"]; ok && v != nil {
+				b, ok := v.(bool)
+				if !ok {
+					return a, refuse("files[%d].delete is true or false. Nothing was sent", i)
+				}
+				fc.Delete = b
+			}
+			a.Files = append(a.Files, fc)
+		}
+	}
+	switch {
+	case len(a.Files) == 0 && strings.TrimSpace(a.Patch) == "":
+		return a, refuse("give files (each {path, content | content_base64 | delete: true}) or patch (a unified diff, as git diff writes it). Nothing was sent")
+	case len(a.Files) > 0 && strings.TrimSpace(a.Patch) != "":
+		return a, refuse("give files or patch, not both: one commit carries one of them. Nothing was sent")
+	case len(a.Files) > maxFiles:
+		return a, refuse("%d files is more than the %d one commit carries. Nothing was sent", len(a.Files), maxFiles)
+	}
+	seen := map[string]bool{}
+	for i, fc := range a.Files {
+		if strings.HasPrefix(fc.Path, "/") {
+			return a, refuse("files[%d].path %q is relative to the repository's root, without a leading slash. Nothing was sent", i, fc.Path)
+		}
+		if _, err := segments("file path", fc.Path); err != nil {
+			return a, err
+		}
+		if seen[fc.Path] {
+			return a, refuse("%s is named twice in files. Nothing was sent", fc.Path)
+		}
+		seen[fc.Path] = true
+		given := 0
+		for _, g := range []bool{fc.Content != nil, fc.ContentBase64 != nil, fc.Delete} {
+			if g {
+				given++
+			}
+		}
+		if given != 1 {
+			return a, refuse("files[%d] (%s) needs exactly one of content, content_base64 or delete: true. Nothing was sent", i, fc.Path)
+		}
+		if fc.Content != nil && !utf8.ValidString(*fc.Content) {
+			return a, refuse("files[%d].content (%s) is not UTF-8 text: give it as content_base64. Nothing was sent", i, fc.Path)
+		}
+		if fc.ContentBase64 != nil {
+			if _, err := base64.StdEncoding.DecodeString(*fc.ContentBase64); err != nil {
+				return a, refuse("files[%d].content_base64 (%s) is not base64: %v. Nothing was sent", i, fc.Path, err)
+			}
+		}
+	}
+	return a, nil
+}
+
+// targetRefused says why a commit may not go on a branch: the default branch, or one a protection rule names.
+func targetRefused(target, defaultBranch string, rules []Protection) error {
+	if target == defaultBranch {
+		return refuse("a commit on %s, the repository's default branch, is refused: a change reaches it by a pull request "+
+			"that passes its checks (novox/hq ADR 0266). Put it on a branch of its own. Nothing was sent", target)
+	}
+	var guarding []string
+	for _, r := range rules {
+		if n := r.name(); n != "" && ruleCovers(n, target) {
+			guarding = append(guarding, n)
+		}
+	}
+	if len(guarding) > 0 {
+		return refuse("a commit on %s is refused: the protection rule %s guards it (novox/hq ADR 0266). Put it on a "+
+			"branch of its own. Nothing was sent", target, strings.Join(guarding, ", "))
+	}
+	return nil
+}
+
+// commit puts one commit on the asked branch, after the judgement, and reads the branch back.
+func commit(ctx context.Context, f *Forge, a CommitAsk) (*Committed, error) {
+	repo, err := repoPath(a.Owner, a.Repo)
+	if err != nil {
+		return nil, err
+	}
+	if _, err := segments("branch", a.Branch); err != nil {
+		return nil, err
+	}
+	var r Repo
+	if err := f.getJSON(ctx, repo, &r); err != nil {
+		return nil, err
+	}
+	if r.DefaultBranch == "" {
+		return nil, fmt.Errorf("the forge did not say %s/%s's default branch, so whether %s is it cannot be judged. Nothing was sent", a.Owner, a.Repo, a.Branch)
+	}
+	// Read the rules, or refuse: a branch the rules could not be read for is never written (fails closed).
+	var rules []Protection
+	if err := f.getJSON(ctx, repo+"/branch_protections", &rules); err != nil {
+		return nil, fmt.Errorf("the protection rules of %s/%s could not be read, so the commit was not judged and nothing was sent: %w", a.Owner, a.Repo, err)
+	}
+	if err := targetRefused(a.Branch, r.DefaultBranch, rules); err != nil {
+		return nil, err
+	}
+
+	out := &Committed{Repository: a.Owner + "/" + a.Repo, Branch: a.Branch}
+	existing, err := f.branch(ctx, repo, a.Branch)
+	if err != nil {
+		return nil, err
+	}
+	ref := a.Branch // where the files are read and the commit goes
+	if existing != nil {
+		out.Parent = existing.Commit.ID
+		if a.Base != "" {
+			out.Said = append(out.Said, fmt.Sprintf("%s exists, at %s: base %s was not used", a.Branch, short(existing.Commit.ID), a.Base))
+		}
+	} else {
+		out.Created = true
+		out.Base = a.Base
+		if out.Base == "" {
+			out.Base = r.DefaultBranch
+		}
+		ref = out.Base
+		b, err := f.branch(ctx, repo, out.Base)
+		if err != nil {
+			return nil, err
+		}
+		if b == nil {
+			return nil, refuse("%s does not exist, and its base %s is not a branch of %s/%s. Nothing was sent", a.Branch, out.Base, a.Owner, a.Repo)
+		}
+		out.Parent = b.Commit.ID
+		// The files are judged at the commit just read; a file the base changes meanwhile is refused by the
+		// forge, whose update and delete carry the blob read here.
+		ref = b.Commit.ID
+	}
+
+	// Where the forge takes the commit: on the branch, or on a new one from the base's commit.
+	on := map[string]any{"message": a.Message}
+	if out.Created {
+		on["branch"] = out.Base
+		on["new_branch"] = a.Branch
+	} else {
+		on["branch"] = a.Branch
+	}
+
+	var made struct {
+		Commit struct {
+			SHA string `json:"sha"`
+		} `json:"commit"`
+	}
+	if a.Patch != "" {
+		on["content"] = a.Patch
+		if err := f.sendJSON(ctx, http.MethodPost, repo+"/diffpatch", on, &made); err != nil {
+			return nil, fmt.Errorf("the forge did not take the patch: %w", err)
+		}
+	} else {
+		var ops []map[string]any
+		for _, fc := range a.Files {
+			sha, err := f.blobAt(ctx, repo, fc.Path, ref)
+			if err != nil {
+				return nil, err
+			}
+			op := map[string]any{"path": fc.Path}
+			switch {
+			case fc.Delete && sha == "":
+				return nil, refuse("%s is to be deleted, but %s has no such file at %s. Nothing was sent", fc.Path, a.Owner+"/"+a.Repo, short(ref))
+			case fc.Delete:
+				op["operation"], op["sha"] = "delete", sha
+			case sha == "":
+				op["operation"] = "create"
+			default:
+				op["operation"], op["sha"] = "update", sha
+			}
+			if !fc.Delete {
+				if fc.Content != nil {
+					op["content"] = base64.StdEncoding.EncodeToString([]byte(*fc.Content))
+				} else {
+					op["content"] = *fc.ContentBase64
+				}
+			}
+			ops = append(ops, op)
+			out.Files = append(out.Files, CommittedFile{Path: fc.Path, Operation: op["operation"].(string)})
+		}
+		on["files"] = ops
+		if err := f.sendJSON(ctx, http.MethodPost, repo+"/contents", on, &made); err != nil {
+			return nil, fmt.Errorf("the forge did not take the commit: %w", err)
+		}
+	}
+	if made.Commit.SHA == "" {
+		return nil, fmt.Errorf("the forge answered the commit on %s without saying the commit it made: read the branch (gitea_list_branches) before trying again", a.Branch)
+	}
+	out.Commit = made.Commit.SHA
+
+	// Evidence over assertion: the branch is read back, and it must be at the commit the forge said.
+	after, err := f.branch(ctx, repo, a.Branch)
+	switch {
+	case err != nil:
+		return nil, fmt.Errorf("the forge made %s on %s, but the branch could not be read back: %w", out.Commit, a.Branch, err)
+	case after == nil:
+		return nil, fmt.Errorf("the forge said it made %s on %s, but the branch does not exist", out.Commit, a.Branch)
+	case after.Commit.ID != out.Commit:
+		return nil, fmt.Errorf("the forge said it made %s on %s, but the branch is at %s: something else moved it", out.Commit, a.Branch, after.Commit.ID)
+	}
+	what := "on"
+	if out.Created {
+		what = "on the new branch"
+	}
+	out.Said = append(out.Said, fmt.Sprintf("%s committed %s %s of %s, after %s; the branch is there now. A merge "+
+		"still needs a review at this head and both required checks green", short(out.Commit), what, a.Branch, out.Repository, short(out.Parent)))
+	return out, nil
+}
+
+// blobAt is the blob sha of a file at a ref, "" when there is no file there.
+func (f *Forge) blobAt(ctx context.Context, repo, path, ref string) (string, error) {
+	seg, err := segments("file path", path)
+	if err != nil {
+		return "", err
+	}
+	var entry struct {
+		Type string `json:"type"`
+		SHA  string `json:"sha"`
+	}
+	var list []any
+	body, err := f.do(ctx, http.MethodGet, repo+"/contents/"+seg+"?ref="+queryEscape(ref), nil, maxBody)
+	if err != nil {
+		if errors.Is(err, errNotFound) {
+			return "", nil
+		}
+		return "", err
+	}
+	if jsonInto(body, &list) == nil {
+		return "", refuse("%s is a directory, not a file. Nothing was sent", path)
+	}
+	if err := jsonInto(body, &entry); err != nil {
+		return "", fmt.Errorf("the forge's answer about %s is not readable: %w", path, err)
+	}
+	if entry.Type != "file" && entry.Type != "symlink" {
+		return "", refuse("%s is a %s, not a file. Nothing was sent", path, entry.Type)
+	}
+	return entry.SHA, nil
+}
+
+func short(sha string) string {
+	if len(sha) > 12 {
+		return sha[:12]
+	}
+	return sha
+}

modules/gitea/cmd/forge/forge.go

@@ -0,0 +1,259 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// The forge as this bundle reaches it: its own HTTP interface on the machine, as the forge's admin account,
+// which the vault delivered into a file this module owns (novox/hq ADR 0086), by basic authentication — the
+// same way the npm-registry bundle beside it does. The password is read when a call is made and never logged,
+// answered or put in an error.
+
+// Forge is the forge's HTTP interface.
+type Forge struct {
+	URL          string // e.g. http://127.0.0.1:3000
+	User         string
+	PasswordFile string
+	HTTP         *http.Client
+}
+
+// ForgeFromEnv is the forge as the manifest hands it to this bundle.
+func ForgeFromEnv() (*Forge, error) {
+	f := &Forge{
+		URL:          strings.TrimRight(os.Getenv("MESH_GITEA_URL"), "/"),
+		User:         os.Getenv("MESH_GITEA_ADMIN_USER"),
+		PasswordFile: os.Getenv("MESH_GITEA_ADMIN_PASSWORD_FILE"),
+	}
+	var missing []string
+	for _, kv := range [][2]string{{"MESH_GITEA_URL", f.URL}, {"MESH_GITEA_ADMIN_USER", f.User},
+		{"MESH_GITEA_ADMIN_PASSWORD_FILE", f.PasswordFile}} {
+		if kv[1] == "" {
+			missing = append(missing, kv[0])
+		}
+	}
+	if len(missing) > 0 {
+		return nil, fmt.Errorf("the forge cannot be reached: %s not set by the manifest", strings.Join(missing, ", "))
+	}
+	return f, nil
+}
+
+// errNotFound is the forge answering 404.
+var errNotFound = errors.New("not found")
+
+// statusError is an answer the forge gave that is not a success, said without the request's credential.
+type statusError struct {
+	method, path string
+	status       int
+	said         string
+}
+
+func (e *statusError) Error() string {
+	return fmt.Sprintf("the forge answered %d to %s %s: %s", e.status, e.method, e.path, e.said)
+}
+
+func (f *Forge) client() *http.Client {
+	if f.HTTP != nil {
+		return f.HTTP
+	}
+	return &http.Client{Timeout: 50 * time.Second}
+}
+
+func (f *Forge) password() (string, error) {
+	raw, err := os.ReadFile(f.PasswordFile)
+	if err != nil {
+		// The path is the manifest's, not a secret; the content never appears.
+		return "", fmt.Errorf("the forge's admin password cannot be read from its file: %w", err)
+	}
+	return strings.TrimSpace(string(raw)), nil
+}
+
+// maxBody is the largest JSON answer read from the forge; maxArchive the largest archive code search reads.
+const (
+	maxBody    = 32 << 20
+	maxArchive = 64 << 20
+)
+
+// do sends one request and answers the body, read up to limit; 404 is errNotFound. A body the limit cut is
+// refused, never read as if it were whole.
+func (f *Forge) do(ctx context.Context, method, path string, payload any, limit int64) ([]byte, error) {
+	password, err := f.password()
+	if err != nil {
+		return nil, err
+	}
+	var body io.Reader
+	if payload != nil {
+		raw, err := json.Marshal(payload)
+		if err != nil {
+			return nil, err
+		}
+		body = bytes.NewReader(raw)
+	}
+	req, err := http.NewRequestWithContext(ctx, method, f.URL+path, body)
+	if err != nil {
+		return nil, err
+	}
+	req.SetBasicAuth(f.User, password)
+	req.Header.Set("Accept", "application/json")
+	if payload != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+	res, err := f.client().Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("the forge did not answer %s %s: %w", method, path, err)
+	}
+	defer res.Body.Close()
+	got, err := io.ReadAll(io.LimitReader(res.Body, limit+1))
+	if err != nil {
+		return nil, err
+	}
+	if int64(len(got)) > limit {
+		return nil, fmt.Errorf("the forge's answer to %s %s is larger than %d MiB and was not read whole", method, path, limit>>20)
+	}
+	switch {
+	case res.StatusCode == http.StatusNotFound:
+		return nil, fmt.Errorf("%s %s: %w", method, path, errNotFound)
+	case res.StatusCode >= 300:
+		said := strings.TrimSpace(string(got))
+		if len(said) > 300 {
+			said = said[:300] + "…"
+		}
+		return nil, &statusError{method, path, res.StatusCode, said}
+	}
+	return got, nil
+}
+
+func (f *Forge) getJSON(ctx context.Context, path string, into any) error {
+	return f.sendJSON(ctx, http.MethodGet, path, nil, into)
+}
+
+func (f *Forge) sendJSON(ctx context.Context, method, path string, payload, into any) error {
+	body, err := f.do(ctx, method, path, payload, maxBody)
+	if err != nil {
+		return err
+	}
+	if into == nil {
+		return nil
+	}
+	if err := json.Unmarshal(body, into); err != nil {
+		return fmt.Errorf("the forge's answer to %s %s is not readable: %w", method, path, err)
+	}
+	return nil
+}
+
+// Refused is a refusal of policy or of an argument, in the words the caller sees.
+type Refused struct{ msg string }
+
+func (r *Refused) Error() string { return r.msg }
+
+func refuse(format string, a ...any) error { return &Refused{fmt.Sprintf(format, a...)} }
+
+var nameShape = regexp.MustCompile(`^[A-Za-z0-9_][A-Za-z0-9_.-]*$`)
+
+// repoPath is /api/v1/repos/{owner}/{repo} for names that cannot become another path.
+func repoPath(owner, repo string) (string, error) {
+	for _, v := range [][2]string{{"owner", owner}, {"name", repo}} {
+		if !nameShape.MatchString(v[1]) || v[1] == "." || v[1] == ".." {
+			return "", refuse("%q is not a repository %s", v[1], v[0])
+		}
+	}
+	return "/api/v1/repos/" + owner + "/" + repo, nil
+}
+
+// segments encodes a value that is several path segments — a branch like fix/1-x, a file's path — refusing
+// any segment that could make the request another path: empty, `.` or `..`, or holding `?`, `#`, `%`, `\`
+// or a control character (the same rule as the TypeScript bundle's pathSegments, guard.ts).
+func segments(what, value string) (string, error) {
+	parts := strings.Split(value, "/")
+	for i, p := range parts {
+		if p == "" || p == "." || p == ".." || strings.ContainsAny(p, "?#%\\") || strings.IndexFunc(p, func(r rune) bool { return r < 0x20 || r == 0x7f }) >= 0 {
+			return "", refuse("%q is not a %s this tool puts in a path. Nothing was sent", value, what)
+		}
+		parts[i] = url.PathEscape(p)
+	}
+	return strings.Join(parts, "/"), nil
+}
+
+// Repo is what the tools read of a repository.
+type Repo struct {
+	FullName      string `json:"full_name"`
+	DefaultBranch string `json:"default_branch"`
+	Empty         bool   `json:"empty"`
+}
+
+// Protection is one branch protection rule, as far as covering a branch goes.
+type Protection struct {
+	RuleName   string `json:"rule_name"`
+	BranchName string `json:"branch_name"`
+}
+
+func (p Protection) name() string {
+	if p.RuleName != "" {
+		return p.RuleName
+	}
+	return p.BranchName
+}
+
+// ruleCovers is whether a protection rule's name — a branch, or a glob of them (`*`, `**`, `?`) — covers a
+// branch: the TypeScript bundle's ruleCovers (guard.ts), which gitea_api's file writes are judged by.
+func ruleCovers(rule, branch string) bool {
+	if rule == branch {
+		return true
+	}
+	if !strings.ContainsAny(rule, "*?[") {
+		return false
+	}
+	var re strings.Builder
+	re.WriteString("^")
+	for i := 0; i < len(rule); i++ {
+		c := rule[i]
+		switch {
+		case c == '*' && i+1 < len(rule) && rule[i+1] == '*':
+			re.WriteString(".*")
+			i++
+		case c == '*':
+			re.WriteString("[^/]*")
+		case c == '?':
+			re.WriteString("[^/]")
+		default:
+			re.WriteString(regexp.QuoteMeta(string(c)))
+		}
+	}
+	re.WriteString("$")
+	ok, err := regexp.MatchString(re.String(), branch)
+	return err == nil && ok
+}
+
+// Branch is one branch with the commit it points at.
+type Branch struct {
+	Name   string `json:"name"`
+	Commit struct {
+		ID string `json:"id"`
+	} `json:"commit"`
+}
+
+// branch is the named branch, nil when the forge has none of that name.
+func (f *Forge) branch(ctx context.Context, repo, name string) (*Branch, error) {
+	seg, err := segments("branch", name)
+	if err != nil {
+		return nil, err
+	}
+	var b Branch
+	if err := f.getJSON(ctx, repo+"/branches/"+seg, &b); err != nil {
+		if errors.Is(err, errNotFound) {
+			return nil, nil
+		}
+		return nil, err
+	}
+	return &b, nil
+}

modules/gitea/cmd/forge/forge_test.go

@@ -0,0 +1,583 @@
+package main
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"crypto/sha1"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+)
+
+// fakeForge is the forge's HTTP interface as far as these tools use it.
+type fakeForge struct {
+	t           *testing.T
+	mu          sync.Mutex
+	password    string
+	branches    map[string]string            // branch -> commit
+	trees       map[string]map[string]string // commit -> path -> content
+	rules       []Protection
+	rulesBroken bool
+	staleRead   bool // the branch is not moved by a write: a forge that says what it did not do
+	writes      []map[string]any
+	patches     []map[string]any
+	next        int
+	archive     []byte
+	pullHead    string
+	reviews     []map[string]any
+	comments    map[string][]map[string]any
+	commits     []map[string]any
+	dir         []map[string]any
+}
+
+func newFake(t *testing.T) *fakeForge {
+	return &fakeForge{
+		t:        t,
+		password: "s3cret-never-shown",
+		branches: map[string]string{"main": "c0", "fix/1-old": "c1"},
+		trees: map[string]map[string]string{
+			"c0": {"README.md": "hello\n", "docs/a.md": "a\n"},
+			"c1": {"README.md": "hello\n", "docs/a.md": "a on fix\n"},
+		},
+		rules: []Protection{{RuleName: "main"}, {RuleName: "release/*"}},
+	}
+}
+
+func blob(content string) string { return fmt.Sprintf("%x", sha1.Sum([]byte(content))) }
+
+func (f *fakeForge) serve() *Forge {
+	dir := f.t.TempDir()
+	pw := filepath.Join(dir, "admin.secret")
+	if err := os.WriteFile(pw, []byte("s3cret-never-shown\n"), 0o600); err != nil {
+		f.t.Fatal(err)
+	}
+	srv := httptest.NewServer(http.HandlerFunc(f.handle))
+	f.t.Cleanup(srv.Close)
+	return &Forge{URL: srv.URL, User: "mesh-admin", PasswordFile: pw}
+}
+
+func (f *fakeForge) handle(w http.ResponseWriter, r *http.Request) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	if u, p, ok := r.BasicAuth(); !ok || u != "mesh-admin" || p != f.password {
+		http.Error(w, "unauthorized", 401)
+		return
+	}
+	reply := func(v any) { _ = json.NewEncoder(w).Encode(v) }
+	const repo = "/api/v1/repos/acme/app"
+	path := r.URL.EscapedPath()
+	switch {
+	case r.Method == "GET" && path == repo:
+		reply(map[string]any{"full_name": "acme/app", "default_branch": "main"})
+	case r.Method == "GET" && path == repo+"/branch_protections":
+		if f.rulesBroken {
+			http.Error(w, "boom", 500)
+			return
+		}
+		reply(f.rules)
+	case r.Method == "GET" && strings.HasPrefix(path, repo+"/branches/"):
+		name := strings.TrimPrefix(r.URL.Path, repo+"/branches/")
+		c, ok := f.branches[name]
+		if !ok {
+			http.NotFound(w, r)
+			return
+		}
+		reply(map[string]any{"name": name, "commit": map[string]any{"id": c}})
+	case r.Method == "GET" && (path == repo+"/contents" || path == repo+"/contents/docs"):
+		reply(f.dir)
+	case r.Method == "GET" && strings.HasPrefix(path, repo+"/contents/"):
+		p := strings.TrimPrefix(r.URL.Path, repo+"/contents/")
+		ref := r.URL.Query().Get("ref")
+		if c, isBranch := f.branches[ref]; isBranch {
+			ref = c
+		}
+		content, ok := f.trees[ref][p]
+		if !ok {
+			http.NotFound(w, r)
+			return
+		}
+		reply(map[string]any{"type": "file", "path": p, "sha": blob(content)})
+	case r.Method == "POST" && path == repo+"/contents":
+		var body map[string]any
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		f.writes = append(f.writes, body)
+		from := f.branches[body["branch"].(string)]
+		tree := map[string]string{}
+		for k, v := range f.trees[from] {
+			tree[k] = v
+		}
+		for _, raw := range body["files"].([]any) {
+			op := raw.(map[string]any)
+			p := op["path"].(string)
+			old, had := tree[p]
+			switch op["operation"] {
+			case "create":
+				if had {
+					http.Error(w, "exists", 422)
+					return
+				}
+			case "update", "delete":
+				if !had || op["sha"] != blob(old) {
+					http.Error(w, "sha does not match", 409)
+					return
+				}
+			}
+			if op["operation"] == "delete" {
+				delete(tree, p)
+				continue
+			}
+			c, _ := base64.StdEncoding.DecodeString(op["content"].(string))
+			tree[p] = string(c)
+		}
+		f.next++
+		made := fmt.Sprintf("n%d", f.next)
+		f.trees[made] = tree
+		target := body["branch"].(string)
+		if nb, ok := body["new_branch"].(string); ok && nb != "" {
+			target = nb
+		}
+		if !f.staleRead {
+			f.branches[target] = made
+		}
+		reply(map[string]any{"commit": map[string]any{"sha": made}})
+	case r.Method == "POST" && path == repo+"/diffpatch":
+		var body map[string]any
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		f.patches = append(f.patches, body)
+		f.next++
+		made := fmt.Sprintf("p%d", f.next)
+		target := body["branch"].(string)
+		if nb, ok := body["new_branch"].(string); ok && nb != "" {
+			target = nb
+		}
+		f.branches[target] = made
+		reply(map[string]any{"commit": map[string]any{"sha": made}})
+	case r.Method == "GET" && path == repo+"/commits":
+		f.writes = append(f.writes, map[string]any{"query": r.URL.RawQuery})
+		reply(f.commits)
+	case r.Method == "GET" && strings.HasPrefix(path, repo+"/compare/"):
+		reply(map[string]any{"total_commits": len(f.commits), "commits": f.commits})
+	case r.Method == "GET" && path == repo+"/pulls/7":
+		reply(map[string]any{"head": map[string]any{"sha": f.pullHead}})
+	case r.Method == "GET" && path == repo+"/pulls/7/reviews":
+		reply(f.reviews)
+	case r.Method == "GET" && strings.HasPrefix(path, repo+"/pulls/7/reviews/") && strings.HasSuffix(path, "/comments"):
+		id := strings.TrimSuffix(strings.TrimPrefix(path, repo+"/pulls/7/reviews/"), "/comments")
+		reply(f.comments[id])
+	case r.Method == "GET" && strings.HasPrefix(path, repo+"/archive/"):
+		_, _ = w.Write(f.archive)
+	default:
+		http.NotFound(w, r)
+	}
+}
+
+func filesArg(files ...map[string]any) []any {
+	out := make([]any, len(files))
+	for i, f := range files {
+		out[i] = f
+	}
+	return out
+}
+
+func ask(t *testing.T, args map[string]any) CommitAsk {
+	t.Helper()
+	base := map[string]any{"owner": "acme", "repo": "app", "message": "Say why"}
+	for k, v := range args {
+		base[k] = v
+	}
+	a, err := readCommitAsk(base)
+	if err != nil {
+		t.Fatalf("ask refused: %v", err)
+	}
+	return a
+}
+
+func TestACommitOnANewBranchCreatesUpdatesAndDeletesInOneCommitFromTheBase(t *testing.T) {
+	f := newFake(t)
+	a := ask(t, map[string]any{"branch": "fix/375-x", "files": filesArg(
+		map[string]any{"path": "new.md", "content": "new\n"},
+		map[string]any{"path": "README.md", "content": "hello again\n"},
+		map[string]any{"path": "docs/a.md", "delete": true},
+	)})
+	got, err := commit(context.Background(), f.serve(), a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !got.Created || got.Base != "main" || got.Parent != "c0" || got.Commit != "n1" || f.branches["fix/375-x"] != "n1" {
+		t.Fatalf("%+v; branches %v", got, f.branches)
+	}
+	if len(f.writes) != 1 {
+		t.Fatalf("%d writes", len(f.writes))
+	}
+	w := f.writes[0]
+	if w["branch"] != "main" || w["new_branch"] != "fix/375-x" || w["message"] != "Say why" {
+		t.Fatalf("sent %v", w)
+	}
+	ops := map[string]string{}
+	for _, raw := range w["files"].([]any) {
+		op := raw.(map[string]any)
+		ops[op["path"].(string)] = op["operation"].(string)
+		if op["operation"] == "create" && op["sha"] != nil {
+			t.Error("a created file carried a sha")
+		}
+	}
+	if ops["new.md"] != "create" || ops["README.md"] != "update" || ops["docs/a.md"] != "delete" {
+		t.Fatalf("ops %v", ops)
+	}
+	tree := f.trees["n1"]
+	if tree["README.md"] != "hello again\n" || tree["new.md"] != "new\n" || tree["docs/a.md"] != "" {
+		t.Fatalf("tree %v", tree)
+	}
+	if f.branches["main"] != "c0" {
+		t.Fatal("main moved")
+	}
+}
+
+func TestACommitOnAnExistingBranchGoesOnItAndReadsItsFilesThere(t *testing.T) {
+	f := newFake(t)
+	a := ask(t, map[string]any{"branch": "fix/1-old", "base": "main",
+		"files": filesArg(map[string]any{"path": "docs/a.md", "content": "a fixed\n"})})
+	got, err := commit(context.Background(), f.serve(), a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got.Created || got.Parent != "c1" || f.branches["fix/1-old"] != got.Commit {
+		t.Fatalf("%+v", got)
+	}
+	if _, has := f.writes[0]["new_branch"]; has || f.writes[0]["branch"] != "fix/1-old" {
+		t.Fatalf("sent %v", f.writes[0])
+	}
+	if !strings.Contains(strings.Join(got.Said, " "), "base main was not used") {
+		t.Errorf("an unused base was not said: %v", got.Said)
+	}
+}
+
+func TestTheDefaultBranchAndProtectedBranchesAreRefusedBeforeAnythingIsSent(t *testing.T) {
+	for _, branch := range []string{"main", "release/1.0"} {
+		f := newFake(t)
+		_, err := commit(context.Background(), f.serve(), ask(t, map[string]any{"branch": branch,
+			"files": filesArg(map[string]any{"path": "x", "content": "x"})}))
+		if err == nil || !strings.Contains(err.Error(), "refused") || !strings.Contains(err.Error(), "ADR 0266") {
+			t.Errorf("%s: %v", branch, err)
+		}
+		if len(f.writes)+len(f.patches) != 0 {
+			t.Errorf("%s: something was written", branch)
+		}
+	}
+}
+
+func TestRulesThatCannotBeReadRefuseTheCommit(t *testing.T) {
+	f := newFake(t)
+	f.rulesBroken = true
+	_, err := commit(context.Background(), f.serve(), ask(t, map[string]any{"branch": "fix/2",
+		"files": filesArg(map[string]any{"path": "x", "content": "x"})}))
+	if err == nil || !strings.Contains(err.Error(), "protection rules") || len(f.writes) != 0 {
+		t.Fatalf("%v, %d writes", err, len(f.writes))
+	}
+}
+
+func TestAPatchIsAppliedByTheForgeOnANewBranch(t *testing.T) {
+	f := newFake(t)
+	patch := "diff --git a/README.md b/README.md\n--- a/README.md\n+++ b/README.md\n@@ -1 +1 @@\n-hello\n+hi\n"
+	got, err := commit(context.Background(), f.serve(), ask(t, map[string]any{"branch": "fix/3", "patch": patch}))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(f.patches) != 1 || f.patches[0]["content"] != patch || f.patches[0]["branch"] != "main" || f.patches[0]["new_branch"] != "fix/3" {
+		t.Fatalf("%v", f.patches)
+	}
+	if got.Commit != "p1" || len(f.writes) != 0 {
+		t.Fatalf("%+v", got)
+	}
+}
+
+func TestACommitTheBranchDoesNotShowIsAFailure(t *testing.T) {
+	f := newFake(t)
+	f.staleRead = true
+	_, err := commit(context.Background(), f.serve(), ask(t, map[string]any{"branch": "fix/1-old",
+		"files": filesArg(map[string]any{"path": "x", "content": "x"})}))
+	if err == nil || !strings.Contains(err.Error(), "branch is at c1") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestDeletingAFileThatIsNotThereIsRefused(t *testing.T) {
+	f := newFake(t)
+	_, err := commit(context.Background(), f.serve(), ask(t, map[string]any{"branch": "fix/4",
+		"files": filesArg(map[string]any{"path": "gone.md", "delete": true})}))
+	if err == nil || !strings.Contains(err.Error(), "no such file") || len(f.writes) != 0 {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestAMissingBaseIsRefused(t *testing.T) {
+	f := newFake(t)
+	_, err := commit(context.Background(), f.serve(), ask(t, map[string]any{"branch": "fix/5", "base": "nope",
+		"files": filesArg(map[string]any{"path": "x", "content": "x"})}))
+	if err == nil || !strings.Contains(err.Error(), "base nope is not a branch") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestACommitAskThatCannotBeReadIsRefused(t *testing.T) {
+	one := filesArg(map[string]any{"path": "x", "content": "x"})
+	for name, args := range map[string]map[string]any{
+		"no branch":       {"files": one},
+		"no message":      {"branch": "b", "message": " ", "files": one},
+		"neither":         {"branch": "b"},
+		"both":            {"branch": "b", "files": one, "patch": "diff"},
+		"dot path":        {"branch": "b", "files": filesArg(map[string]any{"path": "a/../b", "content": "x"})},
+		"absolute path":   {"branch": "b", "files": filesArg(map[string]any{"path": "/etc/x", "content": "x"})},
+		"twice":           {"branch": "b", "files": filesArg(map[string]any{"path": "x", "content": "x"}, map[string]any{"path": "x", "delete": true})},
+		"two contents":    {"branch": "b", "files": filesArg(map[string]any{"path": "x", "content": "x", "delete": true})},
+		"no content":      {"branch": "b", "files": filesArg(map[string]any{"path": "x"})},
+		"bad base64":      {"branch": "b", "files": filesArg(map[string]any{"path": "x", "content_base64": "!!"})},
+		"files not list":  {"branch": "b", "files": "x"},
+		"path with query": {"branch": "b", "files": filesArg(map[string]any{"path": "a?b", "content": "x"})},
+	} {
+		full := map[string]any{"owner": "acme", "repo": "app", "message": "m"}
+		for k, v := range args {
+			full[k] = v
+		}
+		if _, err := readCommitAsk(full); err == nil {
+			t.Errorf("%s: taken", name)
+		}
+	}
+	f := newFake(t)
+	_, err := commit(context.Background(), f.serve(), CommitAsk{Owner: "acme", Repo: "app", Branch: "../x", Message: "m", Patch: "d"})
+	if err == nil {
+		t.Error("a branch with a dot segment was taken")
+	}
+}
+
+func TestRuleCoversIsTheGuardsRule(t *testing.T) {
+	for _, c := range []struct {
+		rule, branch string
+		want         bool
+	}{
+		{"main", "main", true}, {"main", "mainx", false}, {"release/*", "release/1.0", true},
+		{"release/*", "release/a/b", false}, {"release/**", "release/a/b", true}, {"v?", "v1", true},
+		{"a.b", "axb", false},
+	} {
+		if got := ruleCovers(c.rule, c.branch); got != c.want {
+			t.Errorf("%s covers %s: %v", c.rule, c.branch, got)
+		}
+	}
+}
+
+func TestHistoryAndCompareAreSummarised(t *testing.T) {
+	f := newFake(t)
+	mk := func(sha, msg string, files ...string) map[string]any {
+		var fs []map[string]any
+		for _, x := range files {
+			fs = append(fs, map[string]any{"filename": x, "status": "modified"})
+		}
+		return map[string]any{"sha": sha, "commit": map[string]any{"message": msg,
+			"author": map[string]any{"name": "jochen", "date": "2026-10-12T10:00:00Z"}}, "files": fs}
+	}
+	f.commits = []map[string]any{mk("a1", "First line\n\nbody", "x.md", "y.md"), mk("a2", "Second", "y.md")}
+	forge := f.serve()
+	h, err := history(context.Background(), forge, "acme", "app", "fix/1", "docs", 2, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(h.Commits) != 2 || h.Commits[0].Subject != "First line" || h.Commits[0].Author != "jochen" || !h.More {
+		t.Fatalf("%+v", h)
+	}
+	q := f.writes[0]["query"].(string)
+	for _, want := range []string{"sha=fix%2F1", "path=docs", "limit=2", "files=false"} {
+		if !strings.Contains(q, want) {
+			t.Errorf("query %s lacks %s", q, want)
+		}
+	}
+	c, err := compare(context.Background(), forge, "acme", "app", "main", "fix/1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if c.Total != 2 || len(c.Files) != 2 || c.Files[0].Path != "x.md" || c.Commits[1].Subject != "Second" {
+		t.Fatalf("%+v", c)
+	}
+	if _, err := compare(context.Background(), forge, "acme", "app", "a...b", "c"); err == nil {
+		t.Error("a ref holding ... was compared")
+	}
+}
+
+func TestReviewsSayWhichApproveTheHeadAndCarryTheirLineComments(t *testing.T) {
+	f := newFake(t)
+	f.pullHead = "h2"
+	f.reviews = []map[string]any{
+		{"id": 1, "user": map[string]any{"login": "reviewer"}, "state": "APPROVED", "commit_id": "h1", "comments_count": 0},
+		{"id": 2, "user": map[string]any{"login": "reviewer"}, "state": "REQUEST_CHANGES", "commit_id": "h2", "comments_count": 1, "body": "see line"},
+		{"id": 3, "user": map[string]any{"login": "op"}, "state": "APPROVED", "commit_id": "h2", "comments_count": 0},
+	}
+	f.comments = map[string][]map[string]any{"2": {{"path": "a.go", "position": 12, "user": map[string]any{"login": "reviewer"},
+		"body": "off by one", "resolver": map[string]any{"login": "op"}}}}
+	r, err := reviews(context.Background(), f.serve(), "acme", "app", 7)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(r.Reviews) != 3 || r.Reviews[0].AtHead || !r.Reviews[1].AtHead || len(r.Reviews[1].Comments) != 1 {
+		t.Fatalf("%+v", r)
+	}
+	lc := r.Reviews[1].Comments[0]
+	if lc.Path != "a.go" || lc.Line != 12 || lc.Resolved != "op" {
+		t.Fatalf("%+v", lc)
+	}
+	if !strings.Contains(r.Said[0], "1 approve the head") {
+		t.Fatalf("%v", r.Said)
+	}
+}
+
+func TestADirectoryIsListed(t *testing.T) {
+	f := newFake(t)
+	f.dir = []map[string]any{{"name": "a.md", "type": "file", "size": 3}, {"name": "sub", "type": "dir", "size": 0}}
+	l, err := listDir(context.Background(), f.serve(), "acme", "app", "/docs/", "main")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if l.Path != "/docs" || len(l.Entries) != 2 || l.Entries[0].Size != 3 || l.Entries[1].Type != "dir" {
+		t.Fatalf("%+v", l)
+	}
+}
+
+func archive(t *testing.T, files map[string]string) []byte {
+	var buf bytes.Buffer
+	zw := gzip.NewWriter(&buf)
+	tw := tar.NewWriter(zw)
+	_ = tw.WriteHeader(&tar.Header{Name: "app/", Typeflag: tar.TypeDir, Mode: 0o755})
+	for name, content := range files {
+		if err := tw.WriteHeader(&tar.Header{Name: "app/" + name, Typeflag: tar.TypeReg, Mode: 0o644, Size: int64(len(content))}); err != nil {
+			t.Fatal(err)
+		}
+		_, _ = tw.Write([]byte(content))
+	}
+	_ = tw.Close()
+	_ = zw.Close()
+	return buf.Bytes()
+}
+
+func TestCodeSearchReadsTheArchiveOnce(t *testing.T) {
+	f := newFake(t)
+	f.archive = archive(t, map[string]string{
+		"docs/a.md":  "one\nthe Forge\nthree forge\n",
+		"src/b.go":   "package b // forge\n",
+		"bin/x":      "forge\x00binary",
+		"docs/c.txt": "nothing\n",
+	})
+	forge := f.serve()
+	found, err := searchCode(context.Background(), forge, SearchAsk{Owner: "acme", Repo: "app", Query: "forge", Max: 100})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(found.Matches) != 2 || found.Ref != "main" || found.Files != 3 {
+		t.Fatalf("%+v", found)
+	}
+	found, _ = searchCode(context.Background(), forge, SearchAsk{Owner: "acme", Repo: "app", Query: "forge", IgnoreCase: true, Path: "docs", Max: 100})
+	if len(found.Matches) != 2 || found.Matches[0].Path != "docs/a.md" || found.Matches[0].Line != 2 {
+		t.Fatalf("%+v", found)
+	}
+	found, _ = searchCode(context.Background(), forge, SearchAsk{Owner: "acme", Repo: "app", Query: "^(one|three)", Regex: true, Max: 1})
+	if len(found.Matches) != 1 || !found.Truncated {
+		t.Fatalf("%+v", found)
+	}
+	if _, err := searchCode(context.Background(), forge, SearchAsk{Owner: "acme", Repo: "app", Query: "(", Regex: true, Max: 1}); err == nil {
+		t.Error("a broken expression was searched")
+	}
+}
+
+func TestAWrongPasswordFailsWithoutSayingIt(t *testing.T) {
+	f := newFake(t)
+	forge := f.serve()
+	f.password = "rotated"
+	_, err := listDir(context.Background(), forge, "acme", "app", "", "")
+	if err == nil || !strings.Contains(err.Error(), "401") || strings.Contains(err.Error(), "s3cret") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestToolsAreTheOnesTheReadmeNamesAndTheManifestBuilds(t *testing.T) {
+	tools := Tools(func() (*Forge, error) { return nil, fmt.Errorf("unset") })
+	var served []string
+	for _, tl := range tools {
+		served = append(served, tl.Name)
+		suffix := "(r)"
+		if tl.Name == "gitea_commit" {
+			suffix = "(a)"
+		}
+		if !strings.HasSuffix(tl.Description, suffix) {
+			t.Errorf("%s does not end with %s", tl.Name, suffix)
+		}
+		if _, err := tl.Run(map[string]any{}); err == nil {
+			t.Errorf("%s ran without a forge", tl.Name)
+		}
+	}
+	if strings.Join(served, ",") != strings.Join(ToolNames, ",") {
+		t.Fatalf("served %v, named %v", served, ToolNames)
+	}
+	readme, err := os.ReadFile("../../README.md")
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, n := range ToolNames {
+		if !strings.Contains(string(readme), "`"+n+"`") {
+			t.Errorf("the README does not name %s", n)
+		}
+	}
+	// No name the TypeScript bundle serves: two bundles serving one name is one tool answered twice.
+	ts, err := os.ReadFile("../../tools/index.ts")
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, n := range ToolNames {
+		if strings.Contains(string(ts), `name: "`+n+`"`) {
+			t.Errorf("the TypeScript bundle serves %s too", n)
+		}
+	}
+	raw, err := os.ReadFile("../../module.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m struct {
+		Tools []string `json:"tools"`
+		Build struct {
+			Artifacts []struct {
+				From   string            `json:"from"`
+				Binary string            `json:"binary"`
+				Loads  []string          `json:"loads"`
+				Env    map[string]string `json:"env"`
+			} `json:"artifacts"`
+		} `json:"build"`
+	}
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	if len(m.Tools) != 0 {
+		t.Error("the manifest lists tools: its claims would offer them as both seats' verbs")
+	}
+	found := false
+	for _, a := range m.Build.Artifacts {
+		if a.From == "cmd/forge" {
+			found = true
+			if len(a.Loads) != 1 || a.Loads[0] != a.Binary {
+				t.Errorf("the bundle loads %v, not its binary %s", a.Loads, a.Binary)
+			}
+			for _, k := range []string{"MESH_GITEA_URL", "MESH_GITEA_ADMIN_USER", "MESH_GITEA_ADMIN_PASSWORD_FILE"} {
+				if a.Env[k] == "" {
+					t.Errorf("the bundle is not given %s", k)
+				}
+			}
+		}
+	}
+	if !found {
+		t.Error("the manifest builds no cmd/forge bundle")
+	}
+}

modules/gitea/cmd/forge/main.go

@@ -0,0 +1,236 @@
+// forge: the forge module's Go bundle for an agent's commit and the reads around it (novox/hq issue 375).
+// A process the node's runtime launches and speaks MCP over stdio to, beside the module's TypeScript bundle
+// and its npm-registry bundle. gitea_commit puts one commit on a branch of its own — never the default branch,
+// never one a protection rule names (novox/hq ADR 0266) — and the reads answer a commit history, a compare, a
+// pull request's reviews with their line comments, a directory's entries and a code search, summarised.
+// stdout is the protocol; it says what it says on stderr, and never the forge's credential.
+package main
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"os"
+	"strings"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+// ToolNames are the tools this bundle serves. The module's manifest lists no `tools` (see the npm-registry
+// bundle for why); the README names these, and a test holds the three together.
+var ToolNames = []string{"gitea_commit", "gitea_commits", "gitea_compare", "gitea_pull_reviews", "gitea_list_dir", "gitea_search_code"}
+
+func main() {
+	if err := stdio.Serve("", Tools(ForgeFromEnv)); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+// Tools are the bundle's tools over the forge the function gives; asked per call, so a manifest that does not
+// set the environment is a refusal naming what is missing, not a bundle that will not start.
+func Tools(forge func() (*Forge, error)) []stdio.Tool {
+	str := func(d string) map[string]any { return map[string]any{"type": "string", "description": d} }
+	owner := str("the repository's owner, e.g. novox")
+	repo := str("the repository's name, e.g. hq")
+	run := func(do func(ctx context.Context, f *Forge, args map[string]any) (any, error)) func(map[string]any) (any, error) {
+		return func(args map[string]any) (any, error) {
+			f, err := forge()
+			if err != nil {
+				return nil, err
+			}
+			ctx, cancel := context.WithTimeout(context.Background(), deadline)
+			defer cancel()
+			return do(ctx, f, args)
+		}
+	}
+	return []stdio.Tool{
+		{
+			Name: "gitea_commit",
+			Description: "Put one commit on a branch of its own in a forge repository, creating the branch from base " +
+				"when it does not exist. Refused on the repository's default branch and on any branch a protection " +
+				"rule names (novox/hq ADR 0266): a change reaches those only by a pull request whose head an " +
+				"independent review approved and whose required checks passed (gitea_merge_pull_request). Carries " +
+				"either files — each {path, content (text) | content_base64 | delete: true}, created or updated as " +
+				"the branch holds them — or patch, a unified diff as git diff writes it, which the forge applies. " +
+				"Answers the commit it made and its parent, read back from the branch. Replaces git commit and git " +
+				"push of a feature branch. (a)",
+			Input: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"owner":   owner,
+					"repo":    repo,
+					"branch":  str("the branch the commit goes on, e.g. fix/375-a-gitea-commit-tool; never the default branch or a protected one"),
+					"base":    str("for a branch that does not exist yet: the branch it starts from (default the repository's default branch)"),
+					"message": str("the commit's message: concise, in the imperative, about why"),
+					"files": map[string]any{
+						"type":        "array",
+						"description": "the files the commit changes; give this or patch",
+						"items": map[string]any{
+							"type": "object",
+							"properties": map[string]any{
+								"path":           str("the file's path from the repository's root"),
+								"content":        str("its whole new content, as UTF-8 text"),
+								"content_base64": str("its whole new content, base64-encoded, for a file that is not text"),
+								"delete":         map[string]any{"type": "boolean", "description": "true to delete the file"},
+							},
+							"required": []string{"path"},
+						},
+					},
+					"patch": str("a unified diff of the change, as git diff or git format-patch writes it; give this or files"),
+				},
+				"required": []string{"owner", "repo", "branch", "message"},
+			},
+			Run: run(func(ctx context.Context, f *Forge, args map[string]any) (any, error) {
+				a, err := readCommitAsk(args)
+				if err != nil {
+					return nil, err
+				}
+				return commit(ctx, f, a)
+			}),
+		},
+		{
+			Name: "gitea_commits",
+			Description: "A repository's commit history at a branch, tag or commit (default the default branch), " +
+				"newest first, optionally only the commits touching a path: each commit's sha, author, date and " +
+				"subject line. Replaces git log. (r)",
+			Input: map[string]any{
+				"owner": owner, "repo": repo,
+				"ref":   str("a branch, tag or commit (default the default branch)"),
+				"path":  str("only commits touching this file or directory"),
+				"limit": map[string]any{"type": "integer", "description": "commits per page, 1 to 100 (default 20)"},
+				"page":  map[string]any{"type": "integer", "description": "the page, from 1 (default 1)"},
+			},
+			Run: run(func(ctx context.Context, f *Forge, args map[string]any) (any, error) {
+				limit, err := count(args, "limit", 20, 1, 100)
+				if err != nil {
+					return nil, err
+				}
+				page, err := count(args, "page", 1, 1, 10000)
+				if err != nil {
+					return nil, err
+				}
+				return history(ctx, f, text(args, "owner"), text(args, "repo"), text(args, "ref"), strings.Trim(text(args, "path"), "/"), limit, page)
+			}),
+		},
+		{
+			Name: "gitea_compare",
+			Description: "What head holds that base does not, in a forge repository: its commits (sha, author, date, " +
+				"subject) and the files they touch with how. Replaces git log base..head and git diff --stat. (r)",
+			Input: map[string]any{
+				"owner": owner, "repo": repo,
+				"base": str("the branch, tag or commit compared from, e.g. main"),
+				"head": str("the branch, tag or commit compared, e.g. fix/375-a-gitea-commit-tool"),
+			},
+			Run: run(func(ctx context.Context, f *Forge, args map[string]any) (any, error) {
+				return compare(ctx, f, text(args, "owner"), text(args, "repo"), text(args, "base"), text(args, "head"))
+			}),
+		},
+		{
+			Name: "gitea_pull_reviews",
+			Description: "A pull request's reviews, oldest first: who, its state (APPROVED, REQUEST_CHANGES, COMMENT, " +
+				"PENDING), the commit it reviewed and whether that is the pull request's head now, stale or dismissed, " +
+				"its body, and every line comment it left (file, line, body, who resolved it). (r)",
+			Input: map[string]any{
+				"owner": owner, "repo": repo,
+				"number": map[string]any{"type": "integer", "description": "the pull request's number"},
+			},
+			Run: run(func(ctx context.Context, f *Forge, args map[string]any) (any, error) {
+				n, err := count(args, "number", 0, 1, math.MaxInt32)
+				if err != nil {
+					return nil, err
+				}
+				if n == 0 {
+					return nil, refuse("number is required: the pull request's number")
+				}
+				return reviews(ctx, f, text(args, "owner"), text(args, "repo"), n)
+			}),
+		},
+		{
+			Name: "gitea_list_dir",
+			Description: "A directory's entries in a forge repository at a branch, tag or commit (default the default " +
+				"branch): each entry's name, its type (file, dir, symlink, submodule) and a file's size. Replaces ls " +
+				"and git ls-tree. (r)",
+			Input: map[string]any{
+				"owner": owner, "repo": repo,
+				"path": str("the directory from the repository's root (default the root)"),
+				"ref":  str("a branch, tag or commit (default the default branch)"),
+			},
+			Run: run(func(ctx context.Context, f *Forge, args map[string]any) (any, error) {
+				return listDir(ctx, f, text(args, "owner"), text(args, "repo"), text(args, "path"), text(args, "ref"))
+			}),
+		},
+		{
+			Name: "gitea_search_code",
+			Description: "Search a forge repository's text files at a branch, tag or commit (default the default " +
+				"branch) for a literal string, or a regular expression with regex: true, optionally under a path: " +
+				"each matching line's file, number and text. The forge has no code search of its own, so the " +
+				"repository's archive is read once and searched; files over 4 MiB are named, not searched. Replaces " +
+				"git grep. (r)",
+			Input: map[string]any{
+				"owner": owner, "repo": repo,
+				"query":       str("what to find: a literal string, or a Go regular expression with regex: true"),
+				"regex":       map[string]any{"type": "boolean", "description": "true to read query as a regular expression"},
+				"ignore_case": map[string]any{"type": "boolean", "description": "true to match regardless of case"},
+				"path":        str("only files under this directory, or this one file"),
+				"ref":         str("a branch, tag or commit (default the default branch)"),
+				"max":         map[string]any{"type": "integer", "description": "the most matches answered, 1 to 1000 (default 100)"},
+			},
+			Run: run(func(ctx context.Context, f *Forge, args map[string]any) (any, error) {
+				max, err := count(args, "max", 100, 1, 1000)
+				if err != nil {
+					return nil, err
+				}
+				regex, err := flag(args, "regex")
+				if err != nil {
+					return nil, err
+				}
+				ignore, err := flag(args, "ignore_case")
+				if err != nil {
+					return nil, err
+				}
+				return searchCode(ctx, f, SearchAsk{Owner: text(args, "owner"), Repo: text(args, "repo"), Ref: text(args, "ref"),
+					Query: raw(args, "query"), Path: text(args, "path"), Regex: regex, IgnoreCase: ignore, Max: max})
+			}),
+		},
+	}
+}
+
+// text is an argument trimmed; raw is it as given.
+func text(args map[string]any, key string) string { return strings.TrimSpace(raw(args, key)) }
+
+func raw(args map[string]any, key string) string {
+	s, _ := args[key].(string)
+	return s
+}
+
+func count(args map[string]any, key string, fallback, least, most int) (int, error) {
+	v, given := args[key]
+	if !given || v == nil {
+		return fallback, nil
+	}
+	x, ok := v.(float64)
+	if !ok || x != math.Trunc(x) {
+		return 0, refuse("%s must be a whole number", key)
+	}
+	if x < float64(least) || x > float64(most) {
+		return 0, refuse("%s must be from %d to %d", key, least, most)
+	}
+	return int(x), nil
+}
+
+func flag(args map[string]any, key string) (bool, error) {
+	v, given := args[key]
+	if !given || v == nil {
+		return false, nil
+	}
+	switch b := v.(type) {
+	case bool:
+		return b, nil
+	case string:
+		if b == "true" || b == "false" {
+			return b == "true", nil
+		}
+	}
+	return false, refuse("%s is true or false, not %v", key, v)
+}

modules/gitea/cmd/forge/reads.go

@@ -0,0 +1,334 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// The forge's reads an agent otherwise made through gitea_api, answered summarised rather than as the forge's
+// JSON (novox/hq issue 375): a commit's history, a compare, a pull request's reviews with their line comments,
+// a directory's entries.
+
+// CommitLine is one commit, summarised.
+type CommitLine struct {
+	SHA     string `json:"sha"`
+	Author  string `json:"author"`
+	Date    string `json:"date"`
+	Subject string `json:"subject"`
+	Files   int    `json:"files,omitempty"`
+}
+
+type forgeCommit struct {
+	SHA    string `json:"sha"`
+	Commit struct {
+		Message string `json:"message"`
+		Author  struct {
+			Name  string `json:"name"`
+			Email string `json:"email"`
+			Date  string `json:"date"`
+		} `json:"author"`
+	} `json:"commit"`
+	Files []struct {
+		Filename string `json:"filename"`
+		Status   string `json:"status"`
+	} `json:"files"`
+}
+
+func (c forgeCommit) line() CommitLine {
+	subject, _, _ := strings.Cut(strings.TrimSpace(c.Commit.Message), "\n")
+	return CommitLine{SHA: c.SHA, Author: c.Commit.Author.Name, Date: c.Commit.Author.Date, Subject: subject, Files: len(c.Files)}
+}
+
+// History is a ref's commits, newest first.
+type History struct {
+	Repository string       `json:"repository"`
+	Ref        string       `json:"ref,omitempty"`
+	Path       string       `json:"path,omitempty"`
+	Page       int          `json:"page"`
+	Commits    []CommitLine `json:"commits"`
+	More       bool         `json:"more"`
+}
+
+func history(ctx context.Context, f *Forge, owner, name, ref, path string, limit, page int) (*History, error) {
+	repo, err := repoPath(owner, name)
+	if err != nil {
+		return nil, err
+	}
+	q := url.Values{}
+	if ref != "" {
+		q.Set("sha", ref)
+	}
+	if path != "" {
+		q.Set("path", path)
+	}
+	q.Set("limit", fmt.Sprint(limit))
+	q.Set("page", fmt.Sprint(page))
+	q.Set("stat", "false")
+	q.Set("verification", "false")
+	q.Set("files", "false")
+	var got []forgeCommit
+	if err := f.getJSON(ctx, repo+"/commits?"+q.Encode(), &got); err != nil {
+		return nil, err
+	}
+	h := &History{Repository: owner + "/" + name, Ref: ref, Path: path, Page: page, Commits: []CommitLine{}, More: len(got) >= limit}
+	for _, c := range got {
+		l := c.line()
+		l.Files = 0
+		h.Commits = append(h.Commits, l)
+	}
+	return h, nil
+}
+
+// Comparison is what head holds that base does not.
+type Comparison struct {
+	Repository string       `json:"repository"`
+	Base       string       `json:"base"`
+	Head       string       `json:"head"`
+	Total      int          `json:"total_commits"`
+	Commits    []CommitLine `json:"commits"`
+	Files      []FileLine   `json:"files"`
+	Said       []string     `json:"said"`
+}
+
+// FileLine is one file a compare touched, and how the last commit that touched it changed it.
+type FileLine struct {
+	Path   string `json:"path"`
+	Status string `json:"status"`
+}
+
+func compare(ctx context.Context, f *Forge, owner, name, base, head string) (*Comparison, error) {
+	repo, err := repoPath(owner, name)
+	if err != nil {
+		return nil, err
+	}
+	b, err := segments("base", base)
+	if err != nil {
+		return nil, err
+	}
+	h, err := segments("head", head)
+	if err != nil {
+		return nil, err
+	}
+	if strings.Contains(base, "...") || strings.Contains(head, "...") {
+		return nil, refuse("a base or head holding ... cannot be compared: the forge splits on it. Nothing was sent")
+	}
+	var got struct {
+		Total   int           `json:"total_commits"`
+		Commits []forgeCommit `json:"commits"`
+	}
+	if err := f.getJSON(ctx, repo+"/compare/"+b+"..."+h, &got); err != nil {
+		return nil, err
+	}
+	c := &Comparison{Repository: owner + "/" + name, Base: base, Head: head, Total: got.Total, Commits: []CommitLine{}, Files: []FileLine{}}
+	at := map[string]int{}
+	for _, fc := range got.Commits {
+		c.Commits = append(c.Commits, fc.line())
+		for _, file := range fc.Files {
+			if i, seen := at[file.Filename]; seen {
+				c.Files[i].Status = file.Status
+				continue
+			}
+			at[file.Filename] = len(c.Files)
+			c.Files = append(c.Files, FileLine{Path: file.Filename, Status: file.Status})
+		}
+	}
+	c.Said = append(c.Said, fmt.Sprintf("%s holds %d commits %s does not, touching %d files", head, got.Total, base, len(c.Files)))
+	if got.Total > len(got.Commits) {
+		c.Said = append(c.Said, fmt.Sprintf("the forge listed %d of the %d commits; the files are those of the commits listed", len(got.Commits), got.Total))
+	}
+	c.Said = append(c.Said, "a file's status is the last listed commit's change to it; for the lines, gitea_pull_request_diff or gitea_get_file")
+	return c, nil
+}
+
+// Review is one review of a pull request with its line comments.
+type Review struct {
+	ID        int64         `json:"id"`
+	By        string        `json:"by"`
+	State     string        `json:"state"`
+	Commit    string        `json:"commit"`
+	AtHead    bool          `json:"at_head"`
+	Submitted string        `json:"submitted,omitempty"`
+	Stale     bool          `json:"stale,omitempty"`
+	Dismissed bool          `json:"dismissed,omitempty"`
+	Official  bool          `json:"official,omitempty"`
+	Body      string        `json:"body,omitempty"`
+	Comments  []LineComment `json:"comments"`
+}
+
+// LineComment is one comment a review left on a line.
+type LineComment struct {
+	Path     string `json:"path"`
+	Line     int    `json:"line,omitempty"`
+	OldLine  int    `json:"old_line,omitempty"`
+	By       string `json:"by"`
+	Body     string `json:"body"`
+	Commit   string `json:"commit,omitempty"`
+	Resolved string `json:"resolved_by,omitempty"`
+}
+
+// Reviews is a pull request's reviews, oldest first.
+type Reviews struct {
+	Repository string   `json:"repository"`
+	Number     int      `json:"number"`
+	Head       string   `json:"head"`
+	Reviews    []Review `json:"reviews"`
+	Said       []string `json:"said"`
+}
+
+type forgeUser struct {
+	Login string `json:"login"`
+}
+
+func reviews(ctx context.Context, f *Forge, owner, name string, number int) (*Reviews, error) {
+	repo, err := repoPath(owner, name)
+	if err != nil {
+		return nil, err
+	}
+	pr := fmt.Sprintf("%s/pulls/%d", repo, number)
+	var pull struct {
+		Head struct {
+			SHA string `json:"sha"`
+		} `json:"head"`
+	}
+	if err := f.getJSON(ctx, pr, &pull); err != nil {
+		if errors.Is(err, errNotFound) {
+			return nil, refuse("%s/%s has no pull request %d", owner, name, number)
+		}
+		return nil, err
+	}
+	out := &Reviews{Repository: owner + "/" + name, Number: number, Head: pull.Head.SHA, Reviews: []Review{}}
+	type forgeReview struct {
+		ID        int64     `json:"id"`
+		User      forgeUser `json:"user"`
+		State     string    `json:"state"`
+		Body      string    `json:"body"`
+		CommitID  string    `json:"commit_id"`
+		Submitted string    `json:"submitted_at"`
+		Stale     bool      `json:"stale"`
+		Dismissed bool      `json:"dismissed"`
+		Official  bool      `json:"official"`
+		Comments  int       `json:"comments_count"`
+	}
+	const page = 50
+	var all []forgeReview
+	for p := 1; ; p++ {
+		var batch []forgeReview
+		if err := f.getJSON(ctx, fmt.Sprintf("%s/reviews?limit=%d&page=%d", pr, page, p), &batch); err != nil {
+			return nil, err
+		}
+		all = append(all, batch...)
+		if len(batch) < page || p >= 20 {
+			break
+		}
+	}
+	approvedAtHead := 0
+	for _, r := range all {
+		rv := Review{ID: r.ID, By: r.User.Login, State: r.State, Commit: r.CommitID, AtHead: r.CommitID != "" && r.CommitID == pull.Head.SHA,
+			Submitted: r.Submitted, Stale: r.Stale, Dismissed: r.Dismissed, Official: r.Official, Body: r.Body, Comments: []LineComment{}}
+		if r.Comments > 0 {
+			var cs []struct {
+				Path     string     `json:"path"`
+				Position int        `json:"position"`
+				Original int        `json:"original_position"`
+				User     forgeUser  `json:"user"`
+				Body     string     `json:"body"`
+				CommitID string     `json:"commit_id"`
+				Resolver *forgeUser `json:"resolver"`
+			}
+			if err := f.getJSON(ctx, fmt.Sprintf("%s/reviews/%d/comments", pr, r.ID), &cs); err != nil {
+				return nil, fmt.Errorf("review %d's line comments could not be read: %w", r.ID, err)
+			}
+			for _, c := range cs {
+				lc := LineComment{Path: c.Path, Line: c.Position, OldLine: c.Original, By: c.User.Login, Body: c.Body, Commit: c.CommitID}
+				if c.Resolver != nil {
+					lc.Resolved = c.Resolver.Login
+				}
+				rv.Comments = append(rv.Comments, lc)
+			}
+		}
+		if rv.AtHead && r.State == "APPROVED" && !r.Dismissed && !r.Stale {
+			approvedAtHead++
+		}
+		out.Reviews = append(out.Reviews, rv)
+	}
+	out.Said = append(out.Said, fmt.Sprintf("%d reviews; %d approve the head %s", len(out.Reviews), approvedAtHead, short(pull.Head.SHA)))
+	return out, nil
+}
+
+// Entry is one entry of a directory.
+type Entry struct {
+	Name string `json:"name"`
+	Type string `json:"type"`
+	Size int64  `json:"size,omitempty"`
+}
+
+// Listing is a directory's entries at a ref.
+type Listing struct {
+	Repository string  `json:"repository"`
+	Path       string  `json:"path"`
+	Ref        string  `json:"ref,omitempty"`
+	Entries    []Entry `json:"entries"`
+}
+
+func listDir(ctx context.Context, f *Forge, owner, name, path, ref string) (*Listing, error) {
+	repo, err := repoPath(owner, name)
+	if err != nil {
+		return nil, err
+	}
+	path = strings.Trim(path, "/")
+	at := repo + "/contents"
+	if path != "" {
+		seg, err := segments("directory path", path)
+		if err != nil {
+			return nil, err
+		}
+		at += "/" + seg
+	}
+	if ref != "" {
+		at += "?ref=" + queryEscape(ref)
+	}
+	body, err := f.do(ctx, "GET", at, nil, maxBody)
+	if err != nil {
+		if errors.Is(err, errNotFound) {
+			return nil, refuse("%s/%s has no %q at %s", owner, name, path, orDefault(ref))
+		}
+		return nil, err
+	}
+	var got []struct {
+		Name string `json:"name"`
+		Type string `json:"type"`
+		Size int64  `json:"size"`
+	}
+	if err := jsonInto(body, &got); err != nil {
+		return nil, refuse("%s is a file, not a directory: gitea_get_file reads it", path)
+	}
+	l := &Listing{Repository: owner + "/" + name, Path: "/" + path, Ref: ref, Entries: []Entry{}}
+	for _, e := range got {
+		en := Entry{Name: e.Name, Type: e.Type}
+		if e.Type == "file" {
+			en.Size = e.Size
+		}
+		l.Entries = append(l.Entries, en)
+	}
+	return l, nil
+}
+
+func orDefault(ref string) string {
+	if ref == "" {
+		return "the default branch"
+	}
+	return ref
+}
+
+func jsonInto(body []byte, into any) error { return json.Unmarshal(body, into) }
+
+// queryEscape is a query value as the forge reads it.
+func queryEscape(v string) string { return url.QueryEscape(v) }
+
+// deadline is how long one tool call may take: inside a module's 60-second ask.
+const deadline = 50 * time.Second

modules/gitea/cmd/forge/search.go

@@ -0,0 +1,171 @@
+package main
+
+import (
+	"archive/tar"
+	"bufio"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"regexp"
+	"strings"
+)
+
+// gitea_search_code: the forge's API has no code search, so the repository's archive at a ref is read once
+// and searched here (novox/hq issue 375). One request, nothing kept.
+
+// Match is one line that matched.
+type Match struct {
+	Path string `json:"path"`
+	Line int    `json:"line"`
+	Text string `json:"text"`
+}
+
+// Found is a search's answer.
+type Found struct {
+	Repository string   `json:"repository"`
+	Ref        string   `json:"ref"`
+	Query      string   `json:"query"`
+	Matches    []Match  `json:"matches"`
+	Files      int      `json:"files_searched"`
+	Skipped    []string `json:"skipped,omitempty"`
+	Truncated  bool     `json:"truncated"`
+	Said       []string `json:"said"`
+}
+
+// SearchAsk is one gitea_search_code call.
+type SearchAsk struct {
+	Owner, Repo, Ref, Query, Path string
+	Regex, IgnoreCase             bool
+	Max                           int
+}
+
+const (
+	maxFileSearched = 4 << 20 // a larger file is skipped and named
+	maxLineShown    = 300
+)
+
+func searchCode(ctx context.Context, f *Forge, a SearchAsk) (*Found, error) {
+	repo, err := repoPath(a.Owner, a.Repo)
+	if err != nil {
+		return nil, err
+	}
+	if a.Query == "" {
+		return nil, refuse("query is required. Nothing was sent")
+	}
+	pattern := a.Query
+	if !a.Regex {
+		pattern = regexp.QuoteMeta(pattern)
+	}
+	if a.IgnoreCase {
+		pattern = "(?i)" + pattern
+	}
+	re, err := regexp.Compile(pattern)
+	if err != nil {
+		return nil, refuse("query is not a regular expression Go reads: %v. Nothing was sent", err)
+	}
+	ref := a.Ref
+	if ref == "" {
+		var r Repo
+		if err := f.getJSON(ctx, repo, &r); err != nil {
+			return nil, err
+		}
+		if r.Empty || r.DefaultBranch == "" {
+			return &Found{Repository: a.Owner + "/" + a.Repo, Query: a.Query, Matches: []Match{}, Said: []string{"the repository is empty"}}, nil
+		}
+		ref = r.DefaultBranch
+	}
+	seg, err := segments("ref", ref)
+	if err != nil {
+		return nil, err
+	}
+	prefix := strings.Trim(a.Path, "/")
+	if prefix != "" {
+		if _, err := segments("path", prefix); err != nil {
+			return nil, err
+		}
+	}
+	body, err := f.do(ctx, "GET", repo+"/archive/"+seg+".tar.gz", nil, maxArchive)
+	if err != nil {
+		if errors.Is(err, errNotFound) {
+			return nil, refuse("%s/%s has no ref %s", a.Owner, a.Repo, ref)
+		}
+		return nil, err
+	}
+	out := &Found{Repository: a.Owner + "/" + a.Repo, Ref: ref, Query: a.Query, Matches: []Match{}}
+	if err := searchArchive(body, prefix, re, a.Max, out); err != nil {
+		return nil, fmt.Errorf("the archive of %s at %s could not be read: %w", out.Repository, ref, err)
+	}
+	said := fmt.Sprintf("%d matches in %d files searched", len(out.Matches), out.Files)
+	if out.Truncated {
+		said = fmt.Sprintf("the first %d matches, and more were found: narrow with path or the query", len(out.Matches))
+	}
+	out.Said = append(out.Said, said)
+	if len(out.Skipped) > 0 {
+		out.Said = append(out.Said, fmt.Sprintf("%d files larger than %d MiB were not searched: they are under skipped", len(out.Skipped), maxFileSearched>>20))
+	}
+	return out, nil
+}
+
+// searchArchive reads a gzipped tar the forge made — every path under one top directory — and collects the
+// lines that match, from text files under the prefix.
+func searchArchive(gz []byte, prefix string, re *regexp.Regexp, max int, out *Found) error {
+	zr, err := gzip.NewReader(bytes.NewReader(gz))
+	if err != nil {
+		return err
+	}
+	tr := tar.NewReader(zr)
+	for {
+		h, err := tr.Next()
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		if h.Typeflag != tar.TypeReg {
+			continue
+		}
+		_, path, found := strings.Cut(h.Name, "/")
+		if !found || path == "" {
+			continue
+		}
+		if prefix != "" && path != prefix && !strings.HasPrefix(path, prefix+"/") {
+			continue
+		}
+		if h.Size > maxFileSearched {
+			out.Skipped = append(out.Skipped, path)
+			continue
+		}
+		content, err := io.ReadAll(io.LimitReader(tr, maxFileSearched+1))
+		if err != nil {
+			return err
+		}
+		head := content
+		if len(head) > 8000 {
+			head = head[:8000]
+		}
+		if bytes.IndexByte(head, 0) >= 0 {
+			continue // binary
+		}
+		out.Files++
+		sc := bufio.NewScanner(bytes.NewReader(content))
+		sc.Buffer(make([]byte, 64<<10), maxFileSearched+1)
+		for n := 1; sc.Scan(); n++ {
+			line := sc.Text()
+			if !re.MatchString(line) {
+				continue
+			}
+			if len(out.Matches) >= max {
+				out.Truncated = true
+				return nil
+			}
+			if len(line) > maxLineShown {
+				line = strings.ToValidUTF8(line[:maxLineShown], "") + "…"
+			}
+			out.Matches = append(out.Matches, Match{Path: path, Line: n, Text: line})
+		}
+	}
+}