Remove unreachable utility functions (bd-224, bd-214)

- Remove duplicate computeIssueContentHash from sqlite/hash.go
- Remove FileUsed() from internal/config/config.go
- Remove verifyIssueOpen() test helper from git_sync_test.go
- Remove unimplemented SummarizeTier2 and all tier2 infrastructure from haiku.go

Removes ~120 LOC of dead code identified by deadcode analyzer.

Amp-Thread-ID: https://ampcode.com/threads/T-5f150c35-8d67-4dae-bb92-a7b5887d649d
Co-authored-by: Amp <amp@ampcode.com>

internal/compact/haiku.go

@@ -30,7 +30,6 @@ type HaikuClient struct {
 	client         anthropic.Client
 	model          anthropic.Model
 	tier1Template  *template.Template
-	tier2Template  *template.Template
 	maxRetries     int
 	initialBackoff time.Duration
 }
@@ -52,16 +51,10 @@ func NewHaikuClient(apiKey string) (*HaikuClient, error) {
 		return nil, fmt.Errorf("failed to parse tier1 template: %w", err)
 	}
 
-	tier2Tmpl, err := template.New("tier2").Parse(tier2PromptTemplate)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse tier2 template: %w", err)
-	}
-
 	return &HaikuClient{
 		client:         client,
 		model:          defaultModel,
 		tier1Template:  tier1Tmpl,
-		tier2Template:  tier2Tmpl,
 		maxRetries:     maxRetries,
 		initialBackoff: initialBackoff,
 	}, nil
@@ -77,16 +70,6 @@ func (h *HaikuClient) SummarizeTier1(ctx context.Context, issue *types.Issue) (s
 	return h.callWithRetry(ctx, prompt)
 }
 
-// SummarizeTier2 creates an ultra-compressed single-paragraph summary (≤150 words).
-func (h *HaikuClient) SummarizeTier2(ctx context.Context, issue *types.Issue) (string, error) {
-	prompt, err := h.renderTier2Prompt(issue)
-	if err != nil {
-		return "", fmt.Errorf("failed to render prompt: %w", err)
-	}
-
-	return h.callWithRetry(ctx, prompt)
-}
-
 func (h *HaikuClient) callWithRetry(ctx context.Context, prompt string) (string, error) {
 	var lastErr error
 	params := anthropic.MessageNewParams{
@@ -186,26 +169,6 @@ func (h *HaikuClient) renderTier1Prompt(issue *types.Issue) (string, error) {
 	return string(w.buf), nil
 }
 
-type tier2Data struct {
-	Title              string
-	CurrentDescription string
-}
-
-func (h *HaikuClient) renderTier2Prompt(issue *types.Issue) (string, error) {
-	var buf []byte
-	w := &bytesWriter{buf: buf}
-
-	data := tier2Data{
-		Title:              issue.Title,
-		CurrentDescription: issue.Description,
-	}
-
-	if err := h.tier2Template.Execute(w, data); err != nil {
-		return "", err
-	}
-	return string(w.buf), nil
-}
-
 type bytesWriter struct {
 	buf []byte
 }
@@ -243,17 +206,3 @@ Provide a summary in this exact format:
 **Key Decisions:** [Brief bullet points of only the most important technical choices]
 
 **Resolution:** [One sentence on final outcome and lasting impact]`
-
-const tier2PromptTemplate = `You are performing ultra-compression on a closed software issue. The issue has already been summarized once. Your task is to create a single concise paragraph (≤150 words) that captures the essence.
-
-**Title:** {{.Title}}
-
-**Current Summary:**
-{{.CurrentDescription}}
-
-Provide a single paragraph that covers:
-- What was built/fixed
-- Why it mattered
-- Any lasting impact or decisions
-
-Keep it under 150 words while retaining the most important context.`

internal/compact/haiku_test.go

@@ -90,38 +90,6 @@ func TestRenderTier1Prompt(t *testing.T) {
 	}
 }
 
-func TestRenderTier2Prompt(t *testing.T) {
-	client, err := NewHaikuClient("test-key")
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	issue := &types.Issue{
-		ID:          "bd-1",
-		Title:       "Fix authentication bug",
-		Description: "**Summary:** Fixed OAuth login flow by adding proper error handling.",
-		Status:      types.StatusClosed,
-	}
-
-	prompt, err := client.renderTier2Prompt(issue)
-	if err != nil {
-		t.Fatalf("failed to render prompt: %v", err)
-	}
-
-	if !strings.Contains(prompt, "Fix authentication bug") {
-		t.Error("prompt should contain title")
-	}
-	if !strings.Contains(prompt, "Fixed OAuth login flow") {
-		t.Error("prompt should contain current description")
-	}
-	if !strings.Contains(prompt, "150 words") {
-		t.Error("prompt should contain word limit")
-	}
-	if !strings.Contains(prompt, "ultra-compression") {
-		t.Error("prompt should indicate ultra-compression")
-	}
-}
-
 func TestRenderTier1Prompt_HandlesEmptyFields(t *testing.T) {
 	client, err := NewHaikuClient("test-key")
 	if err != nil {