feat(10-04): add GistSource for public gist keyword recon

- GistSource implements recon.ReconSource (RECON-CODE-04)
- Lists /gists/public?per_page=100, fetches each file's raw content,
  scans against provider keyword set, emits one Finding per matching gist
- Disabled when GitHub token empty
- Rate: rate.Every(2s), burst 1 (30 req/min GitHub limit)
- 256KB read cap per file; skips gists without keyword matches
- httptest coverage: enable gating, sweep match, no-match, 401, ctx cancel

pkg/recon/sources/gist.go

@@ -0,0 +1,184 @@
+package sources
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"golang.org/x/time/rate"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+	"github.com/salvacybersec/keyhunter/pkg/recon"
+)
+
+// GistSource scans recent public GitHub Gists for provider keyword leaks
+// (RECON-CODE-04).
+//
+// GitHub does not expose a dedicated /search/gists endpoint, so this source
+// enumerates /gists/public (most-recent page) and fetches each file's raw URL
+// to scan its content against the provider keyword set. Keep Phase 10 minimal:
+// only the first page is walked; broader sweeps are a future optimization.
+//
+// Auth: GitHub token via Bearer header. Rate: 30 req/min (shared with GitHub
+// search limits) → rate.Every(2s), burst 1.
+type GistSource struct {
+	Token    string
+	BaseURL  string
+	Registry *providers.Registry
+	Limiters *recon.LimiterRegistry
+
+	client *Client
+}
+
+var _ recon.ReconSource = (*GistSource)(nil)
+
+// Name returns the stable source identifier.
+func (s *GistSource) Name() string { return "gist" }
+
+// RateLimit reports the per-source token bucket rate (30/min).
+func (s *GistSource) RateLimit() rate.Limit { return rate.Every(2 * time.Second) }
+
+// Burst reports the token bucket burst capacity.
+func (s *GistSource) Burst() int { return 1 }
+
+// RespectsRobots reports whether robots.txt applies (REST API → false).
+func (s *GistSource) RespectsRobots() bool { return false }
+
+// Enabled reports whether the source runs. Requires a GitHub token.
+func (s *GistSource) Enabled(_ recon.Config) bool { return s.Token != "" }
+
+type gistListEntry struct {
+	HTMLURL string `json:"html_url"`
+	Files   map[string]struct {
+		Filename string `json:"filename"`
+		RawURL   string `json:"raw_url"`
+	} `json:"files"`
+}
+
+// Sweep fetches /gists/public, scans each file's raw content against the
+// keyword set from the registry, and emits one Finding per gist that matches
+// any keyword (not one per file — gists often split a single leak across
+// helper files).
+func (s *GistSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	if s.client == nil {
+		s.client = NewClient()
+	}
+	base := s.BaseURL
+	if base == "" {
+		base = "https://api.github.com"
+	}
+
+	keywords := s.keywordSet()
+	if len(keywords) == 0 {
+		return nil
+	}
+
+	if s.Limiters != nil {
+		if err := s.Limiters.Wait(ctx, s.Name(), s.RateLimit(), s.Burst(), false); err != nil {
+			return err
+		}
+	}
+
+	listReq, err := http.NewRequest(http.MethodGet, base+"/gists/public?per_page=100", nil)
+	if err != nil {
+		return fmt.Errorf("gist: build list request: %w", err)
+	}
+	listReq.Header.Set("Authorization", "Bearer "+s.Token)
+	listReq.Header.Set("Accept", "application/vnd.github+json")
+
+	listResp, err := s.client.Do(ctx, listReq)
+	if err != nil {
+		return fmt.Errorf("gist: list: %w", err)
+	}
+	var gists []gistListEntry
+	dec := json.NewDecoder(listResp.Body)
+	decodeErr := dec.Decode(&gists)
+	_ = listResp.Body.Close()
+	if decodeErr != nil {
+		return fmt.Errorf("gist: decode list: %w", decodeErr)
+	}
+
+	for _, g := range gists {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		matched := false
+		var matchedProvider string
+
+	fileLoop:
+		for _, f := range g.Files {
+			if f.RawURL == "" {
+				continue
+			}
+			if s.Limiters != nil {
+				if err := s.Limiters.Wait(ctx, s.Name(), s.RateLimit(), s.Burst(), false); err != nil {
+					return err
+				}
+			}
+
+			rawReq, err := http.NewRequest(http.MethodGet, f.RawURL, nil)
+			if err != nil {
+				return fmt.Errorf("gist: build raw request: %w", err)
+			}
+			rawReq.Header.Set("Authorization", "Bearer "+s.Token)
+			rawResp, err := s.client.Do(ctx, rawReq)
+			if err != nil {
+				return fmt.Errorf("gist: fetch raw: %w", err)
+			}
+			// Cap read to 256KB to avoid pathological gists.
+			body, readErr := io.ReadAll(io.LimitReader(rawResp.Body, 256*1024))
+			_ = rawResp.Body.Close()
+			if readErr != nil {
+				return fmt.Errorf("gist: read raw: %w", readErr)
+			}
+
+			content := string(body)
+			for kw, provName := range keywords {
+				if strings.Contains(content, kw) {
+					matched = true
+					matchedProvider = provName
+					break fileLoop
+				}
+			}
+		}
+
+		if matched {
+			select {
+			case out <- recon.Finding{
+				ProviderName: matchedProvider,
+				Source:       g.HTMLURL,
+				SourceType:   "recon:gist",
+				DetectedAt:   time.Now().UTC(),
+			}:
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+	}
+
+	return nil
+}
+
+// keywordSet flattens the registry into a keyword→providerName map for
+// content scanning. Empty keywords are skipped.
+func (s *GistSource) keywordSet() map[string]string {
+	out := make(map[string]string)
+	if s.Registry == nil {
+		return out
+	}
+	for _, p := range s.Registry.List() {
+		for _, k := range p.Keywords {
+			if k == "" {
+				continue
+			}
+			if _, ok := out[k]; !ok {
+				out[k] = p.Name
+			}
+		}
+	}
+	return out
+}

pkg/recon/sources/gist_test.go

@@ -0,0 +1,166 @@
+package sources
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+	"github.com/salvacybersec/keyhunter/pkg/recon"
+)
+
+func gistTestRegistry() *providers.Registry {
+	return providers.NewRegistryFromProviders([]providers.Provider{
+		{Name: "openai", Keywords: []string{"sk-proj-"}},
+	})
+}
+
+func newGistSource(baseURL, token string) *GistSource {
+	return &GistSource{
+		Token:    token,
+		BaseURL:  baseURL,
+		Registry: gistTestRegistry(),
+		Limiters: recon.NewLimiterRegistry(),
+	}
+}
+
+func TestGist_EnabledRequiresToken(t *testing.T) {
+	cfg := recon.Config{}
+	if newGistSource("", "").Enabled(cfg) {
+		t.Fatal("expected disabled when token empty")
+	}
+	if !newGistSource("", "tok").Enabled(cfg) {
+		t.Fatal("expected enabled when token set")
+	}
+}
+
+func TestGist_SweepEmitsFindingsOnKeywordMatch(t *testing.T) {
+	var gotAuth, gotListPath string
+
+	mux := http.NewServeMux()
+	var srv *httptest.Server
+
+	mux.HandleFunc("/gists/public", func(w http.ResponseWriter, r *http.Request) {
+		gotAuth = r.Header.Get("Authorization")
+		gotListPath = r.URL.Path
+		w.Header().Set("Content-Type", "application/json")
+		body := fmt.Sprintf(`[
+			{
+				"html_url": "https://gist.github.com/alice/aaa",
+				"files": {
+					"leak.env": {"filename": "leak.env", "raw_url": "%s/raw/aaa"}
+				}
+			},
+			{
+				"html_url": "https://gist.github.com/bob/bbb",
+				"files": {
+					"notes.md": {"filename": "notes.md", "raw_url": "%s/raw/bbb"}
+				}
+			}
+		]`, srv.URL, srv.URL)
+		_, _ = w.Write([]byte(body))
+	})
+	mux.HandleFunc("/raw/aaa", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("OPENAI_API_KEY=sk-proj-1234567890abcdefghijk"))
+	})
+	mux.HandleFunc("/raw/bbb", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("just some unrelated notes here"))
+	})
+
+	srv = httptest.NewServer(mux)
+	t.Cleanup(srv.Close)
+
+	src := newGistSource(srv.URL, "tok")
+	out := make(chan recon.Finding, 8)
+	if err := src.Sweep(context.Background(), "", out); err != nil {
+		t.Fatalf("Sweep: %v", err)
+	}
+	close(out)
+
+	if gotAuth != "Bearer tok" {
+		t.Errorf("Authorization = %q", gotAuth)
+	}
+	if gotListPath != "/gists/public" {
+		t.Errorf("list path = %q", gotListPath)
+	}
+
+	var findings []recon.Finding
+	for f := range out {
+		findings = append(findings, f)
+	}
+	if len(findings) != 1 {
+		t.Fatalf("findings count = %d, want 1 (only aaa matches sk-proj-)", len(findings))
+	}
+	f := findings[0]
+	if !strings.Contains(f.Source, "alice/aaa") {
+		t.Errorf("Source = %q, want gist alice/aaa", f.Source)
+	}
+	if f.SourceType != "recon:gist" {
+		t.Errorf("SourceType = %q", f.SourceType)
+	}
+	if f.ProviderName != "openai" {
+		t.Errorf("ProviderName = %q, want openai", f.ProviderName)
+	}
+}
+
+func TestGist_NoMatch_NoFinding(t *testing.T) {
+	var srv *httptest.Server
+	mux := http.NewServeMux()
+	mux.HandleFunc("/gists/public", func(w http.ResponseWriter, r *http.Request) {
+		body := fmt.Sprintf(`[{"html_url":"https://gist.github.com/x/y","files":{"a.txt":{"filename":"a.txt","raw_url":"%s/raw/x"}}}]`, srv.URL)
+		_, _ = w.Write([]byte(body))
+	})
+	mux.HandleFunc("/raw/x", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("nothing interesting"))
+	})
+	srv = httptest.NewServer(mux)
+	t.Cleanup(srv.Close)
+
+	src := newGistSource(srv.URL, "tok")
+	out := make(chan recon.Finding, 4)
+	if err := src.Sweep(context.Background(), "", out); err != nil {
+		t.Fatalf("Sweep: %v", err)
+	}
+	close(out)
+	n := 0
+	for range out {
+		n++
+	}
+	if n != 0 {
+		t.Fatalf("findings = %d, want 0", n)
+	}
+}
+
+func TestGist_Unauthorized(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "bad", http.StatusUnauthorized)
+	}))
+	t.Cleanup(srv.Close)
+	src := newGistSource(srv.URL, "tok")
+	out := make(chan recon.Finding, 1)
+	err := src.Sweep(context.Background(), "", out)
+	if !errors.Is(err, ErrUnauthorized) {
+		t.Fatalf("err = %v, want ErrUnauthorized", err)
+	}
+}
+
+func TestGist_ContextCancellation(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(2 * time.Second)
+		_, _ = w.Write([]byte(`[]`))
+	}))
+	t.Cleanup(srv.Close)
+	src := newGistSource(srv.URL, "tok")
+	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+	defer cancel()
+	out := make(chan recon.Finding, 1)
+	err := src.Sweep(ctx, "", out)
+	if err == nil {
+		t.Fatal("expected error on cancelled ctx")
+	}
+}