feat: complete v0.3.1 agent workflow

internal/tools/apply_patch.go

@@ -0,0 +1,153 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+
+	"agentu/pkg/llm"
+)
+
+// ────────────────────────────────────────────────────────────────────────────
+// ApplyPatchTool — multi-file patch using V4 format
+// ────────────────────────────────────────────────────────────────────────────
+
+type ApplyPatchTool struct {
+	workingDir string
+}
+
+func NewApplyPatchTool(workingDir string) *ApplyPatchTool {
+	return &ApplyPatchTool{workingDir: workingDir}
+}
+
+// MutatingTool interface.
+
+func (*ApplyPatchTool) Mutates() bool { return true }
+
+// CallMutatingTool — dry_run is non-mutating.
+func (t *ApplyPatchTool) MutatesCall(args json.RawMessage) bool {
+	var a applyPatchArgs
+	if err := json.Unmarshal(args, &a); err != nil {
+		return true // conservative
+	}
+	return !a.DryRun
+}
+
+// PreviewableTool interface.
+
+func (t *ApplyPatchTool) Preview(ctx context.Context, args json.RawMessage) (string, error) {
+	var a applyPatchArgs
+	if err := json.Unmarshal(args, &a); err != nil {
+		return "", fmt.Errorf("parse arguments: %w", err)
+	}
+	return summarizePatch(a.Patch)
+}
+
+// TargetPathTool interface.
+
+func (t *ApplyPatchTool) TargetPaths(args json.RawMessage) ([]string, error) {
+	var a applyPatchArgs
+	if err := json.Unmarshal(args, &a); err != nil {
+		return nil, fmt.Errorf("parse arguments: %w", err)
+	}
+	return extractTargetPaths(t.workingDir, a.Patch)
+}
+
+// Definition.
+
+func (t *ApplyPatchTool) Definition() llm.Tool {
+	return llm.Tool{
+		Type: "function",
+		Function: llm.ToolFunction{
+			Name:        "apply_patch",
+			Description: "Apply a multi-file patch to create, update, or delete files. Uses a V4 diff format with *** Begin Patch / *** Add File / *** Update File / *** Delete File markers. Prefer this over multiple file_edit calls when changing 2+ files.",
+			Parameters: JSONSchema(`{
+  "type": "object",
+  "properties": {
+    "patch": {"type": "string", "description": "V4 format patch text. Must start with *** Begin Patch and end with *** End Patch."},
+    "dry_run": {"type": "boolean", "description": "Preview the patch without writing any files."}
+  },
+  "required": ["patch"],
+  "additionalProperties": false
+}`),
+		},
+	}
+}
+
+type applyPatchArgs struct {
+	Patch  string `json:"patch"`
+	DryRun bool   `json:"dry_run"`
+}
+
+// Execute.
+
+func (t *ApplyPatchTool) Execute(ctx context.Context, raw json.RawMessage) (string, error) {
+	var args applyPatchArgs
+	if err := json.Unmarshal(raw, &args); err != nil {
+		return "", fmt.Errorf("parse arguments: %w", err)
+	}
+
+	if strings.TrimSpace(args.Patch) == "" {
+		return "", fmt.Errorf("patch is empty")
+	}
+
+	pp, err := parsePatch(args.Patch)
+	if err != nil {
+		return "", err
+	}
+
+	if args.DryRun {
+		summary, err := summarizePatch(args.Patch)
+		if err != nil {
+			return "", err
+		}
+		return "dry run — " + summary, nil
+	}
+
+	rollback := NewRollbackStore()
+	var snapshotIDs []string
+	for _, pf := range pp.files {
+		path, err := resolvePathForWrite(t.workingDir, pf.path)
+		if err != nil {
+			return "", err
+		}
+		id, err := rollback.Capture("apply_patch", pf.path, path)
+		if err != nil {
+			return "", err
+		}
+		snapshotIDs = append(snapshotIDs, id)
+	}
+
+	var results []string
+	for _, pf := range pp.files {
+		if err := ctx.Err(); err != nil {
+			if rollbackErr := restoreSnapshots(rollback, snapshotIDs); rollbackErr != nil {
+				return "", fmt.Errorf("%w; rollback failed: %v", err, rollbackErr)
+			}
+			return "", err
+		}
+		result, err := applyPatchFile(t.workingDir, pf)
+		if err != nil {
+			if rollbackErr := restoreSnapshots(rollback, snapshotIDs); rollbackErr != nil {
+				return "", fmt.Errorf("apply patch: %w; rollback failed: %v", err, rollbackErr)
+			}
+			return "", fmt.Errorf("apply patch: %w", err)
+		}
+		results = append(results, result)
+	}
+
+	summary := fmt.Sprintf("applied patch: %d file(s) changed\n%s", len(results), strings.Join(results, "\n"))
+	return summary, nil
+}
+
+func restoreSnapshots(store *RollbackStore, ids []string) error {
+	var errs []error
+	for i := len(ids) - 1; i >= 0; i-- {
+		if _, err := store.Restore(ids[i]); err != nil {
+			errs = append(errs, err)
+		}
+	}
+	return errors.Join(errs...)
+}