test(coverage): remaining test hooks + lint fixes

cmd/sin-code/internal/attachments/attachments.go

@@ -34,7 +34,6 @@ var (
 	osReadDir       = os.ReadDir
 )
 
-
 type Attachment struct {
 	ID        string    `json:"id"`
 	Hash      string    `json:"hash"`

cmd/sin-code/internal/attachments/attachments_test.go

@@ -391,11 +391,11 @@ func TestGetInfoError(t *testing.T) {
 
 type infoErrEntry string
 
-func (e infoErrEntry) Name() string                { return string(e) }
-func (e infoErrEntry) IsDir() bool                 { return false }
-func (e infoErrEntry) Type() os.FileMode           { return 0 }
-func (e infoErrEntry) Info() (os.FileInfo, error)  { return nil, fmt.Errorf("info error") }
-func (e infoErrEntry) String() string              { return string(e) }
+func (e infoErrEntry) Name() string               { return string(e) }
+func (e infoErrEntry) IsDir() bool                { return false }
+func (e infoErrEntry) Type() os.FileMode          { return 0 }
+func (e infoErrEntry) Info() (os.FileInfo, error) { return nil, fmt.Errorf("info error") }
+func (e infoErrEntry) String() string             { return string(e) }
 
 func TestGetPrefixMismatch(t *testing.T) {
 	dir := t.TempDir()

cmd/sin-code/internal/superpowers/superpowers.go

@@ -33,6 +33,26 @@ var DefaultRepoURL = "https://github.com/obra/superpowers.git"
 // corpus on `main`.
 const DefaultBranch = "main"
 
+// testHook variables expose hard-to-reach error paths to the test suite
+// without heavy refactoring. They are restored per-test via t.Cleanup.
+var (
+	osUserHomeDir     = os.UserHomeDir
+	osMkdirAll        = os.MkdirAll
+	osStat            = os.Stat
+	osReadFile        = os.ReadFile
+	osWriteFile       = os.WriteFile
+	osCreateTemp      = os.CreateTemp
+	osRenameHook      = os.Rename
+	jsonMarshalIndent = json.MarshalIndent
+	jsonUnmarshal     = json.Unmarshal
+	ioCopyHook        = io.Copy
+	fileWriteHook     = func(f *os.File, p []byte) (int, error) { return f.Write(p) }
+	fileCloseHook     = func(f *os.File) error { return f.Close() }
+	runGitHook        = runGit
+	currentShaHook    = currentSHA
+	currentBranchHook = currentBranch
+)
+
 // OverlayMarker is the sentinel HTML comment that delimiters the
 // automatically-appended overlay block. Idempotency: if the marker is
 // already present in a SKILL.md, AppendOverlay is a no-op for that file.
@@ -49,7 +69,7 @@ func Home() string {
 		return v
 	}
 	// Use os.UserHomeDir for cross-platform safety (macOS/Linux/Windows).
-	if h, err := os.UserHomeDir(); err == nil {
+	if h, err := osUserHomeDir(); err == nil {
 		return filepath.Join(h, ".local", "share", "sin-code")
 	}
 	// Last resort: cwd-relative fallback so the function is total.
@@ -124,25 +144,25 @@ func Install(ctx context.Context, repoURL, branch string) (*InstallResult, error
 	}
 	start := time.Now()
 	dst := SkillsDir()
-	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+	if err := osMkdirAll(filepath.Dir(dst), 0o755); err != nil {
 		return nil, fmt.Errorf("mkdir: %w", err)
 	}
-	if _, err := os.Stat(filepath.Join(dst, ".git")); err == nil {
-		if err := runGit(ctx, dst, "fetch", "--depth", "1", "origin", branch); err != nil {
+	if _, err := osStat(filepath.Join(dst, ".git")); err == nil {
+		if err := runGitHook(ctx, dst, "fetch", "--depth", "1", "origin", branch); err != nil {
 			return nil, err
 		}
-		if err := runGit(ctx, dst, "reset", "--hard", "FETCH_HEAD"); err != nil {
+		if err := runGitHook(ctx, dst, "reset", "--hard", "FETCH_HEAD"); err != nil {
 			return nil, err
 		}
 	} else {
-		if err := os.MkdirAll(dst, 0o755); err != nil {
+		if err := osMkdirAll(dst, 0o755); err != nil {
 			return nil, fmt.Errorf("mkdir dst: %w", err)
 		}
-		if err := runGit(ctx, ".", "clone", "--depth", "1", "--branch", branch, repoURL, dst); err != nil {
+		if err := runGitHook(ctx, ".", "clone", "--depth", "1", "--branch", branch, repoURL, dst); err != nil {
 			return nil, err
 		}
 	}
-	sha, err := currentSHA(ctx, dst)
+	sha, err := currentShaHook(ctx, dst)
 	if err != nil {
 		return nil, err
 	}

cmd/sin-code/internal/trace/provider.go

@@ -41,9 +41,9 @@ const defaultShutdownTimeout = 5 * time.Second
 
 // Test hooks for error paths.
 var (
-	stdouttraceNew    = stdouttrace.New
-	otlptracehttpNew  = otlptracehttp.New
-	resourceNew       = resource.New
+	stdouttraceNew   = stdouttrace.New
+	otlptracehttpNew = otlptracehttp.New
+	resourceNew      = resource.New
 )
 
 // ProviderConfig configures InitProvider.

cmd/sin-code/internal/vane/mcpserver.go

@@ -170,7 +170,7 @@ func (s *Server) dispatch(ctx context.Context, req *jsonRPCRequest) *jsonRPCResp
 }
 
 func (s *Server) result(req *jsonRPCRequest, v any) *jsonRPCResponse {
-	data, err := json.Marshal(v)
+	data, err := jsonMarshalFn(v)
 	if err != nil {
 		return &jsonRPCResponse{
 			JSONRPC: "2.0",

cmd/sin-code/internal/vane/vane.go

@@ -23,6 +23,23 @@
 	"github.com/OpenSIN-Code/SIN-Code/cmd/sin-code/internal/circuitbreaker"
 )
 
+// testHook variables allow tests to inject failure without heavy
+// refactoring. They are package-level vars (not build-tagged) so the
+// production binary pays only the indirection cost.
+var (
+	osUserHomeDirFn     = os.UserHomeDir
+	osExecutableFn      = os.Executable
+	jsonMarshalFn       = json.Marshal
+	jsonMarshalIndentFn = json.MarshalIndent
+	ioCopyNFn           = io.CopyN
+	ioReadAllFn         = io.ReadAll
+	osMkdirAllFn        = os.MkdirAll
+	osCreateTempFn      = os.CreateTemp
+	writeJSONCopyFn     = io.Copy
+	writeJSONWriteFn    = func(w io.Writer, p []byte) (int, error) { return w.Write(p) }
+	writeJSONCloseFn    = func(c io.Closer) error { return c.Close() }
+)
+
 // ── Public configuration constants ─────────────────────────────────────
 
 // ServerName is the MCP server name registered in mcp.json. Used by
@@ -62,7 +79,7 @@
 		return v
 	}
 	// Use os.UserHomeDir for cross-platform safety (macOS/Linux/Windows).
-	if h, err := os.UserHomeDir(); err == nil {
+	if h, err := osUserHomeDirFn(); err == nil {
 		return filepath.Join(h, ".local", "share", "sin-code")
 	}
 	// Last resort: cwd-relative fallback so the function is total.
@@ -430,28 +447,28 @@
 // directories are created on demand. Mirrors superpowers.WriteJSON() so
 // the rest of the codebase has a consistent persistence semantic.
 func writeJSONAtomic(path string, v any) error {
-	data, err := json.MarshalIndent(v, "", "  ")
+	data, err := jsonMarshalIndentFn(v, "", "  ")
 	if err != nil {
 		return err
 	}
-	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+	if err := osMkdirAllFn(filepath.Dir(path), 0o755); err != nil {
 		return err
 	}
-	tmp, err := os.CreateTemp(filepath.Dir(path), ".vane-*.json.tmp")
+	tmp, err := osCreateTempFn(filepath.Dir(path), ".vane-*.json.tmp")
 	if err != nil {
 		return err
 	}
 	tmpName := tmp.Name()
 	defer os.Remove(tmpName)
-	if _, err := io.Copy(tmp, bytes.NewReader(data)); err != nil {
-		tmp.Close()
+	if _, err := writeJSONCopyFn(tmp, bytes.NewReader(data)); err != nil {
+		writeJSONCloseFn(tmp)
 		return err
 	}
-	if _, err := tmp.Write([]byte("\n")); err != nil {
-		tmp.Close()
+	if _, err := writeJSONWriteFn(tmp, []byte("\n")); err != nil {
+		writeJSONCloseFn(tmp)
 		return err
 	}
-	if err := tmp.Close(); err != nil {
+	if err := writeJSONCloseFn(tmp); err != nil {
 		return err
 	}
 	return os.Rename(tmpName, path)

cmd/sin-code/tui/agent_runner_adapter.go

@@ -11,6 +11,7 @@
 package tui
 
 import (
+	"context"
 	"fmt"
 	"strings"
 
@@ -30,6 +31,16 @@
 // initAgentRunner lazily initializes the agent runner used for chat
 // submits. Returns the runner or nil if it could not be constructed.
 // The caller is responsible for calling Close() when the TUI exits.
+// newAgentRunnerHook is a test seam for AgentRunner construction.
+var newAgentRunnerHook = func(ctx context.Context, cfg agentrunner.Config) (*agentrunner.AgentRunner, error) {
+	return agentrunner.NewAgentRunner(ctx, cfg)
+}
+
+// submitAgentRunnerHook is a test seam for AgentRunner submission.
+var submitAgentRunnerHook = func(r *agentrunner.AgentRunner, ctx context.Context, prompt string) (string, error) {
+	return r.Submit(ctx, prompt)
+}
+
 func (m *Model) initAgentRunner() *agentrunner.AgentRunner {
 	if m.AgentRunner != nil {
 		return m.AgentRunner
@@ -38,7 +49,7 @@
 	if ws == "" {
 		ws = "."
 	}
-	r, err := agentrunner.NewAgentRunner(m.ctx(), agentrunner.Config{
+	r, err := newAgentRunnerHook(m.ctx(), agentrunner.Config{
 		Workspace: ws,
 		Headless:  false, // TUI is interactive — show the Ask dialog
 		Yolo:      false, // never auto-allow in interactive mode
@@ -122,7 +133,7 @@
 	if r == nil {
 		return nil
 	}
-	if _, err := r.Submit(m.ctx(), prompt); err != nil {
+	if _, err := submitAgentRunnerHook(r, m.ctx(), prompt); err != nil {
 		m.ChatHistory = append(m.ChatHistory,
 			"assistant: (agent runner unavailable: "+err.Error()+")")
 		if len(m.ChatHistory) > 500 {
@@ -151,7 +162,7 @@
 		return nil
 	}
 	prompt := fmt.Sprintf("use the %s tool to %s", skill, args)
-	if _, err := r.Submit(m.ctx(), prompt); err != nil {
+	if _, err := submitAgentRunnerHook(r, m.ctx(), prompt); err != nil {
 		m.ChatHistory = append(m.ChatHistory,
 			"assistant: (agent runner error: "+err.Error()+")")
 		if len(m.ChatHistory) > 500 {

cmd/sin-code/tui/chat/input.go

@@ -279,7 +279,7 @@
 		return false
 	}
 	if strings.HasPrefix(trimmed, "~/") {
-		home, err := os.UserHomeDir()
+		home, err := osUserHomeDirHook()
 		if err != nil {
 			return false
 		}

cmd/sin-code/tui/chat/runner.go

@@ -17,6 +17,11 @@ import (
 	"github.com/OpenSIN-Code/SIN-Code/cmd/sin-code/internal/llm"
 )
 
+var (
+	// providerFromConfigHook is overridden in tests to exercise NewRunner error paths.
+	providerFromConfigHook = llm.ProviderFromConfig
+)
+
 const (
 	defaultModel  = "meta/llama-3.3-70b-instruct"
 	defaultSystem = "You are sin-code, an AI coding assistant. Be concise."
@@ -37,7 +42,7 @@ func NewRunner() (*Runner, error) {
 	if os.Getenv("SIN_NIM_API_KEY") == "" {
 		return nil, fmt.Errorf("no API key configured (set SIN_NIM_API_KEY)")
 	}
-	c, err := llm.ProviderFromConfig("nim", "", "", defaultModel, 0)
+	c, err := providerFromConfigHook("nim", "", "", defaultModel, 0)
 	if err != nil {
 		return nil, err
 	}

cmd/sin-code/tui/chat_input.go

@@ -14,6 +14,14 @@
 
 type chatInput = chat.Input
 
+// newChatRunnerHook is a test seam for chat runner construction.
+var newChatRunnerHook = func() (*chat.Runner, error) { return chat.NewRunner() }
+
+// chatRunnerRunHook is a test seam for chat runner execution.
+var chatRunnerRunHook = func(r *chat.Runner, ctx context.Context, prompt string, history []string) (string, error) {
+	return r.Run(ctx, prompt, history)
+}
+
 func newChatInput() *chatInput {
 	store, err := attachments.NewStore()
 	if err != nil {
@@ -35,7 +43,7 @@
 	if m.ChatRunner != nil {
 		return
 	}
-	r, err := chat.NewRunner()
+	r, err := newChatRunnerHook()
 	if err != nil {
 		m.ChatRunner = nil
 		return

cmd/sin/skill_cmds.go

@@ -168,7 +168,7 @@ func runSkillValidate(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return fmt.Errorf("parse error: %w", err)
 	}
-	
+
 	var errors []string
 	if skill.Name == "" {
 		errors = append(errors, "missing skill name (first heading)")
@@ -182,7 +182,7 @@ func runSkillValidate(cmd *cobra.Command, args []string) error {
 	if _, ok := skill.Sections["Anti-Rationalization"]; !ok {
 		errors = append(errors, "missing ## Anti-Rationalization section (recommended)")
 	}
-	
+
 	if len(errors) > 0 {
 		fmt.Printf("❌ Validation failed for %s:\n", path)
 		for _, e := range errors {

internal/headroom/compressor.go

@@ -10,13 +10,13 @@ import (
 // Compressor is the main entry point for headroom compression in SIN-Code.
 // It automatically selects the best available mode (MCP > CLI > disabled).
 type Compressor struct {
-	config   Config
-	mode     Mode
-	cliCli   *CLIClient
-	mcpCli   *MCPClient
-	lessons  *LessonStore
-	enabled  bool
-	stats    atomic.Value // stores *Stats
+	config  Config
+	mode    Mode
+	cliCli  *CLIClient
+	mcpCli  *MCPClient
+	lessons *LessonStore
+	enabled bool
+	stats   atomic.Value // stores *Stats
 }
 
 // SetLessonStore attaches a lesson store so that LearnFromFailure persists

internal/headroom/lessons.go

@@ -16,11 +16,11 @@ import (
 // that previously turned out to be important.
 type Lesson struct {
 	ID        string    `json:"id"`
-	Category  string    `json:"category"`            // e.g. "compression", "retrieval", "tooling"
-	Pattern   string    `json:"pattern"`             // the content pattern that mattered
-	Insight   string    `json:"insight"`             // what was learned
-	Weight    float64   `json:"weight"`              // importance 0..1, higher = keep more
-	Hits      int       `json:"hits"`                // how often this lesson was reinforced
+	Category  string    `json:"category"` // e.g. "compression", "retrieval", "tooling"
+	Pattern   string    `json:"pattern"`  // the content pattern that mattered
+	Insight   string    `json:"insight"`  // what was learned
+	Weight    float64   `json:"weight"`   // importance 0..1, higher = keep more
+	Hits      int       `json:"hits"`     // how often this lesson was reinforced
 	CreatedAt time.Time `json:"created_at"`
 	UpdatedAt time.Time `json:"updated_at"`
 }