wip: P1 feature batch — retry, search, code symbols, diff/status/test commands, tool output head+tail

- retry logic for transient LLM errors (openai.go)
- file_search context_lines + max_results (file.go)
- FormatResult now preserves head+tail with omitted bytes (tools.go)
- /status /diff /test slash commands wired (workflow.go, app.go)
- CodeSymbolsTool for Go package/type/func listing (code.go)
- README updated with v0.0.4 features

internal/llm/openai.go

@@ -10,8 +10,13 @@ import (
 	"io"
 	"net/http"
 	"strings"
+	"time"
 )
 
+const maxChatAttempts = 3
+
+const retryDelay = 100 * time.Millisecond
+
 type OpenAICompatibleClient struct {
 	baseURL    string
 	apiKey     string
@@ -36,29 +41,69 @@ func (c *OpenAICompatibleClient) ChatStream(ctx context.Context, req ChatRequest
 		return fmt.Errorf("marshal chat request: %w", err)
 	}
 
-	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/v1/chat/completions", bytes.NewReader(body))
-	if err != nil {
-		return fmt.Errorf("create chat request: %w", err)
-	}
-	httpReq.Header.Set("Content-Type", "application/json")
-	httpReq.Header.Set("Accept", "text/event-stream")
-	if c.apiKey != "" {
-		httpReq.Header.Set("Authorization", "Bearer "+c.apiKey)
-	}
+	var lastErr error
+	for attempt := 1; attempt <= maxChatAttempts; attempt++ {
+		httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/v1/chat/completions", bytes.NewReader(body))
+		if err != nil {
+			return fmt.Errorf("create chat request: %w", err)
+		}
+		httpReq.Header.Set("Content-Type", "application/json")
+		httpReq.Header.Set("Accept", "text/event-stream")
+		if c.apiKey != "" {
+			httpReq.Header.Set("Authorization", "Bearer "+c.apiKey)
+		}
 
-	resp, err := c.httpClient.Do(httpReq)
-	if err != nil {
-		return fmt.Errorf("send chat request: %w", err)
-	}
-	defer resp.Body.Close()
+		resp, err := c.httpClient.Do(httpReq)
+		if err != nil {
+			lastErr = fmt.Errorf("send chat request: %w", err)
+			if !shouldRetryRequest(ctx, attempt, 0) {
+				return lastErr
+			}
+			if waitErr := waitBeforeRetry(ctx); waitErr != nil {
+				return waitErr
+			}
+			continue
+		}
 
-	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
-		limit := io.LimitReader(resp.Body, 4096)
-		data, _ := io.ReadAll(limit)
-		return fmt.Errorf("chat request failed: status=%d body=%s", resp.StatusCode, strings.TrimSpace(string(data)))
-	}
+		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+			limit := io.LimitReader(resp.Body, 4096)
+			data, _ := io.ReadAll(limit)
+			_ = resp.Body.Close()
+			lastErr = fmt.Errorf("chat request failed: status=%d body=%s", resp.StatusCode, strings.TrimSpace(string(data)))
+			if !shouldRetryRequest(ctx, attempt, resp.StatusCode) {
+				return lastErr
+			}
+			if waitErr := waitBeforeRetry(ctx); waitErr != nil {
+				return waitErr
+			}
+			continue
+		}
 
-	return readSSE(resp.Body, emit)
+		defer resp.Body.Close()
+		return readSSE(resp.Body, emit)
+	}
+	return lastErr
+}
+
+func shouldRetryRequest(ctx context.Context, attempt int, status int) bool {
+	if ctx.Err() != nil || attempt >= maxChatAttempts {
+		return false
+	}
+	if status == 0 {
+		return true
+	}
+	return status == http.StatusRequestTimeout || status == http.StatusTooManyRequests || status >= 500
+}
+
+func waitBeforeRetry(ctx context.Context) error {
+	timer := time.NewTimer(retryDelay)
+	defer timer.Stop()
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-timer.C:
+		return nil
+	}
 }
 
 func readSSE(r io.Reader, emit func(StreamEvent) error) error {

internal/llm/openai_test.go

@@ -66,6 +66,37 @@ func TestOpenAICompatibleClientStreamsContentAndToolCalls(t *testing.T) {
 	}
 }
 
+func TestOpenAICompatibleClientRetriesTransientHTTPError(t *testing.T) {
+	attempts := 0
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			http.Error(w, "temporary", http.StatusBadGateway)
+			return
+		}
+		w.Header().Set("Content-Type", "text/event-stream")
+		_, _ = w.Write([]byte(`data: {"choices":[{"delta":{"content":"ok"},"finish_reason":""}]}` + "\n\n"))
+		_, _ = w.Write([]byte("data: [DONE]\n\n"))
+	}))
+	defer server.Close()
+
+	client := NewOpenAICompatibleClient(server.URL, "sk-test", server.Client())
+	var content strings.Builder
+	err := client.ChatStream(context.Background(), ChatRequest{Model: "test"}, func(event StreamEvent) error {
+		content.WriteString(event.Content)
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if attempts != 2 {
+		t.Fatalf("attempts = %d, want 2", attempts)
+	}
+	if content.String() != "ok" {
+		t.Fatalf("content = %q", content.String())
+	}
+}
+
 func mustReadBody(t *testing.T, r *http.Request) string {
 	t.Helper()
 	data, err := io.ReadAll(r.Body)