feat: symlink preserved files instead of copying them

README.md

@@ -486,18 +486,16 @@ strategy = "squash"  # squash, rebase, or merge
 
 ### Preserve Settings
 
-Automatically copy git-ignored files (`.env`, `.envrc`, etc.) from an existing worktree when checking out a new one with `wt checkout`. Useful for keeping local configuration in sync across worktrees.
+Symlink files from the repo root into new worktrees created with `wt checkout`. Useful for keeping local configuration (`.env`, `.envrc`, etc.) in sync across worktrees — edits in any worktree are instantly visible in all others.
 
 ```toml
 [preserve]
-patterns = [".env", ".env.*", ".envrc", "docker-compose.override.yml"]
-exclude = ["node_modules", ".cache", "vendor"]
+paths = [".env", ".envrc"]
 ```
 
-- **patterns** — glob patterns matched against file basenames; only git-ignored files are considered
-- **exclude** — path segments to skip (any component match excludes the file)
+- **paths** — relative paths from the repo root to symlink (e.g., `".env"`, `"config/.env"`)
 
-Files are copied from the worktree on the default branch, e.g. `main` (or the first available worktree). Existing files are never overwritten. Symlinks are skipped. Use `--no-preserve` on `wt checkout` to skip.
+Paths that don't exist in the repo root are silently skipped. Existing files in the target worktree are never overwritten. Use `--no-preserve` on `wt checkout` to skip.
 
 ### Self-Hosted Instances
 
@@ -563,8 +561,7 @@ delete_local_branches = true  # replaces global
 default = "gitlab"            # replaces global
 
 [preserve]
-patterns = [".env.local"]     # appended to global (deduplicated)
-exclude = ["dist"]            # appended to global (deduplicated)
+paths = [".env.local"]        # appended to global (deduplicated)
 
 # Hooks merge by name — add new hooks or override global ones
 [hooks.setup]

cmd/wt/checkout_cmd.go

@@ -2,9 +2,7 @@ package main
 
 import (
 	"context"
-	"errors"
 	"fmt"
-	"path/filepath"
 	"slices"
 
 	"github.com/spf13/cobra"
@@ -208,7 +206,7 @@ func checkoutInRepo(ctx context.Context, repo registry.Repo, branch string, opts
 		}
 	}
 
-	preserveWorktreeFiles(ctx, gitDir, wtPath, opts.NoPreserve, cfg.Preserve)
+	preserveWorktreeFiles(ctx, repo.Path, wtPath, opts.NoPreserve, cfg.Preserve)
 
 	action := hooks.ActionOpen
 	if opts.NewBranch {
@@ -340,29 +338,19 @@ func setUpstreamTracking(ctx context.Context, gitDir, branch string, newBranch,
 	}
 }
 
-// preserveWorktreeFiles copies git-ignored files from an existing worktree to the new one.
-func preserveWorktreeFiles(ctx context.Context, gitDir, wtPath string, noPreserve bool, preserveCfg config.PreserveConfig) {
-	if noPreserve || len(preserveCfg.Patterns) == 0 {
+// preserveWorktreeFiles symlinks preserved files from the repo root into the new worktree.
+func preserveWorktreeFiles(ctx context.Context, repoPath, wtPath string, noPreserve bool, preserveCfg config.PreserveConfig) {
+	if noPreserve || len(preserveCfg.Paths) == 0 {
 		return
 	}
 	l := log.FromContext(ctx)
 
-	sourceWT, err := preserve.FindSourceWorktree(ctx, gitDir, wtPath)
-	if err != nil {
-		if errors.Is(err, preserve.ErrNoSourceWorktree) {
-			l.Debug("preserve: no source worktree found")
-		} else {
-			l.Printf("Warning: preserve: %v\n", err)
-		}
-		return
-	}
-
-	copied, err := preserve.PreserveFiles(ctx, preserveCfg, sourceWT, wtPath)
+	linked, err := preserve.PreserveFiles(ctx, preserveCfg, repoPath, wtPath)
 	if err != nil {
 		l.Printf("Warning: preserve files failed: %v\n", err)
-	} else if len(copied) > 0 {
-		l.Printf("Preserved %d file(s) from %s\n", len(copied), filepath.Base(sourceWT))
-		for _, f := range copied {
+	} else if len(linked) > 0 {
+		l.Printf("Preserved %d file(s)\n", len(linked))
+		for _, f := range linked {
 			l.Debug("  preserved", "file", f)
 		}
 	}