Add forest query commands (list, show, rename)

src/erk/cli/cli.py

@@ -50,14 +50,14 @@ def cli(ctx: click.Context) -> None:
 cli.add_command(up_cmd)
 cli.add_command(list_cmd)
 cli.add_command(ls_cmd)
-cli.add_command(split_cmd)
 cli.add_command(status_cmd)
 cli.add_command(init_cmd)
 cli.add_command(move_cmd)
 cli.add_command(delete_cmd)
 cli.add_command(del_cmd)
 cli.add_command(rename_cmd)
 cli.add_command(config_group)
+cli.add_command(split_cmd)
 cli.add_command(sync_cmd)
 cli.add_command(hidden_shell_cmd)
 cli.add_command(prepare_cwd_recovery_cmd)

src/erk/cli/commands/forest/__init__.py

@@ -2,14 +2,10 @@
 
 import click
 
-# TODO: Implement forest subcommands
-# from erk.cli.commands.forest.list import list_forests
-# from erk.cli.commands.forest.merge import merge_forest
-# from erk.cli.commands.forest.rename import rename_forest
-# from erk.cli.commands.forest.reroot import reroot_forest
-# from erk.cli.commands.forest.show import show_forest
-# from erk.cli.commands.forest.show_current import show_current_forest
-# from erk.cli.commands.forest.split import split_forest
+from erk.cli.commands.forest.list import list_forests
+from erk.cli.commands.forest.rename import rename_forest
+from erk.cli.commands.forest.show import show_forest
+from erk.cli.commands.forest.show_current import show_current_forest
 
 
 @click.group("forest", invoke_without_command=True)
@@ -22,16 +18,13 @@ def forest_group(ctx: click.Context) -> None:
 
     When called without a subcommand, shows the forest for the current worktree.
     """
-    # If no subcommand is provided, show placeholder message
+    # If no subcommand is provided, show current forest
     if ctx.invoked_subcommand is None:
-        click.echo("Forest command infrastructure in progress.")
-        click.echo("Subcommands will be available in a future release.")
+        from erk.cli.commands.forest.show_current import show_current_forest
+        ctx.invoke(show_current_forest)
 
 
-# Register subcommands (TODO: uncomment when implemented)
-# forest_group.add_command(list_forests)
-# forest_group.add_command(show_forest)
-# forest_group.add_command(rename_forest)
-# forest_group.add_command(split_forest)
-# forest_group.add_command(merge_forest)
-# forest_group.add_command(reroot_forest)
+# Register subcommands
+forest_group.add_command(list_forests)
+forest_group.add_command(show_forest)
+forest_group.add_command(rename_forest)

src/erk/cli/commands/forest/list.py

@@ -0,0 +1,63 @@
+"""List all forests command."""
+
+from datetime import datetime
+
+import click
+
+from erk.cli.output import user_output
+from erk.core.context import ErkContext
+from erk.core.repo_discovery import NoRepoSentinel, RepoContext
+
+
+def format_date(iso_timestamp: str) -> str:
+    """Format ISO 8601 timestamp to human-readable date.
+
+    Args:
+        iso_timestamp: ISO 8601 format timestamp
+
+    Returns:
+        Formatted date like "2024-01-15"
+    """
+    dt = datetime.fromisoformat(iso_timestamp.replace("Z", "+00:00"))
+    return dt.strftime("%Y-%m-%d")
+
+
+@click.command("list", help="List all forests in repository")
+@click.pass_obj
+def list_forests(ctx: ErkContext) -> None:
+    """List all forests in repository.
+
+    Displays forest name, worktree count, and creation date.
+    Sorted by creation date (newest first).
+    """
+    if isinstance(ctx.repo, NoRepoSentinel):
+        user_output(
+            click.style("Error: ", fg="red")
+            + "Not in a repository. This command requires a git repository."
+        )
+        raise SystemExit(1)
+
+    # Load forests
+    metadata = ctx.forest_ops.load_forests()
+
+    if not metadata.forests:
+        user_output("No forests in repository.")
+        raise SystemExit(0)
+
+    # Get repository name for header
+    repo: RepoContext = ctx.repo  # Type narrowing
+    repo_name = repo.root.name
+
+    # Sort forests by creation date (newest first)
+    sorted_forests = sorted(metadata.forests.values(), key=lambda f: f.created_at, reverse=True)
+
+    # Display header
+    user_output(f"Forests in {click.style(repo_name, bold=True)}:")
+
+    # Display each forest
+    for forest in sorted_forests:
+        forest_name = click.style(forest.name, fg="cyan", bold=True)
+        count = f"({len(forest.worktrees)} worktrees)"
+        date = f"created {format_date(forest.created_at)}"
+
+        user_output(f"• {forest_name} {count} - {date}")

src/erk/cli/commands/forest/rename.py

@@ -0,0 +1,82 @@
+"""Rename forest command."""
+
+import click
+
+from erk.cli.output import user_output
+from erk.core.context import ErkContext
+from erk.core.forest_utils import rename_forest as rename_forest_util
+from erk.core.forest_utils import validate_forest_name
+from erk.core.repo_discovery import NoRepoSentinel
+
+
+@click.command("rename", help="Rename a forest (label only, paths unchanged)")
+@click.argument("old_name")
+@click.argument("new_name")
+@click.pass_obj
+def rename_forest(ctx: ErkContext, old_name: str, new_name: str) -> None:
+    """Rename a forest (label only, paths unchanged).
+
+    This changes the forest label in metadata. Worktree paths remain unchanged.
+
+    Args:
+        old_name: Current forest name
+        new_name: New forest name
+    """
+    if isinstance(ctx.repo, NoRepoSentinel):
+        user_output(
+            click.style("Error: ", fg="red")
+            + "Not in a repository. This command requires a git repository."
+        )
+        raise SystemExit(1)
+
+    # Validate new name
+    if not validate_forest_name(new_name):
+        user_output(
+            click.style("Error: ", fg="red")
+            + f"Invalid forest name: '{new_name}'\n\n"
+            + "Forest names must be:\n"
+            + "• Non-empty\n"
+            + "• Max 30 characters\n"
+            + "• Alphanumeric + hyphens only"
+        )
+        raise SystemExit(1)
+
+    # Load forests
+    metadata = ctx.forest_ops.load_forests()
+
+    # Validate old_name exists
+    if old_name not in metadata.forests:
+        available = ", ".join(metadata.forests.keys()) if metadata.forests else "(none)"
+        user_output(
+            click.style("Error: ", fg="red")
+            + f"Forest '{old_name}' does not exist\n\n"
+            + f"Available forests: {available}"
+        )
+        raise SystemExit(1)
+
+    # Validate new_name doesn't conflict
+    if new_name in metadata.forests:
+        user_output(
+            click.style("Error: ", fg="red")
+            + f"Forest '{new_name}' already exists\n\n"
+            + "Choose a different name."
+        )
+        raise SystemExit(1)
+
+    # Perform rename
+    updated_metadata = rename_forest_util(metadata, old_name, new_name)
+
+    # Save
+    ctx.forest_ops.save_forests(updated_metadata)
+
+    # Display success
+    user_output(
+        click.style("✓", fg="green")
+        + f" Renamed forest '{click.style(old_name, fg='yellow')}' to "
+        + f"'{click.style(new_name, fg='cyan', bold=True)}'"
+    )
+    user_output()
+    user_output(
+        click.style("Note: ", fg="white", dim=True)
+        + "This only changes the forest label. Worktree paths remain unchanged."
+    )

src/erk/cli/commands/forest/show.py

@@ -0,0 +1,99 @@
+"""Show specific forest command."""
+
+import click
+
+from erk.cli.output import user_output
+from erk.core.context import ErkContext
+from erk.core.forest_utils import find_forest_by_worktree
+from erk.core.repo_discovery import NoRepoSentinel
+from erk.core.worktree_utils import find_current_worktree
+
+
+@click.command("show", help="Show details of a specific forest")
+@click.argument("name", required=False)
+@click.pass_obj
+def show_forest(ctx: ErkContext, name: str | None) -> None:
+    """Show details of a specific forest.
+
+    If name is not provided, shows the forest for the current worktree.
+
+    Args:
+        name: Optional forest name to show
+    """
+    if isinstance(ctx.repo, NoRepoSentinel):
+        user_output(
+            click.style("Error: ", fg="red")
+            + "Not in a repository. This command requires a git repository."
+        )
+        raise SystemExit(1)
+
+    # Load forests
+    metadata = ctx.forest_ops.load_forests()
+
+    # Determine which forest to show
+    if name is None:
+        # Default to current worktree's forest
+        worktrees = ctx.git_ops.list_worktrees(ctx.repo.root)
+        current_wt_info = find_current_worktree(worktrees, ctx.cwd)
+
+        if current_wt_info is None:
+            user_output(
+                click.style("Error: ", fg="red")
+                + "Not in a worktree and no forest name provided.\n\n"
+                + "Usage: erk forest show [NAME]"
+            )
+            raise SystemExit(1)
+
+        worktree_name = current_wt_info.path.name
+        forest = find_forest_by_worktree(metadata, worktree_name)
+
+        if forest is None:
+            user_output(
+                click.style("Error: ", fg="red")
+                + "Current worktree is not in a forest.\n\n"
+                + "Use 'erk forest list' to see all forests."
+            )
+            raise SystemExit(1)
+
+        current_worktree = worktree_name
+    else:
+        # Show specified forest
+        if name not in metadata.forests:
+            available = ", ".join(metadata.forests.keys()) if metadata.forests else "(none)"
+            user_output(
+                click.style("❌ Error: ", fg="red")
+                + f"Forest '{name}' not found\n\n"
+                + f"Available forests: {available}"
+            )
+            raise SystemExit(1)
+
+        forest = metadata.forests[name]
+
+        # Try to determine current worktree
+        worktrees = ctx.git_ops.list_worktrees(ctx.repo.root)
+        current_wt_info = find_current_worktree(worktrees, ctx.cwd)
+        current_worktree = (
+            current_wt_info.path.name
+            if current_wt_info and current_wt_info.path.name in forest.worktrees
+            else None
+        )
+
+    # Display forest
+    forest_header = click.style(f"Forest: {forest.name}", fg="cyan", bold=True)
+    count_text = f" ({len(forest.worktrees)} worktrees)"
+    user_output(forest_header + count_text)
+
+    # Display worktrees in tree format
+    for idx, wt in enumerate(forest.worktrees):
+        is_last = idx == len(forest.worktrees) - 1
+        prefix = "└──" if is_last else "├──"
+
+        # Highlight current worktree
+        wt_display = click.style(wt, fg="yellow")
+        branch_display = f"[{wt}]"
+
+        if wt == current_worktree:
+            indicator = click.style(" ← you are here", fg="bright_green", bold=True)
+            user_output(f"{prefix} {wt_display} {branch_display}{indicator}")
+        else:
+            user_output(f"{prefix} {wt_display} {branch_display}")

src/erk/cli/commands/forest/show_current.py

@@ -0,0 +1,66 @@
+"""Show current worktree's forest command."""
+
+import click
+
+from erk.cli.output import user_output
+from erk.core.context import ErkContext
+from erk.core.forest_utils import find_forest_by_worktree
+from erk.core.repo_discovery import NoRepoSentinel
+from erk.core.worktree_utils import find_current_worktree
+
+
+@click.command("forest", help="Show forest for current worktree")
+@click.pass_obj
+def show_current_forest(ctx: ErkContext) -> None:
+    """Show forest for current worktree.
+
+    Displays the forest name and all worktrees in the forest,
+    highlighting the current worktree.
+    """
+    if isinstance(ctx.repo, NoRepoSentinel):
+        user_output(
+            click.style("Error: ", fg="red")
+            + "Not in a repository. This command requires a git repository."
+        )
+        raise SystemExit(1)
+
+    # Get current worktree
+    worktrees = ctx.git_ops.list_worktrees(ctx.repo.root)
+    current_wt = find_current_worktree(worktrees, ctx.cwd)
+
+    if current_wt is None:
+        user_output("Current directory is not in an erk worktree.")
+        raise SystemExit(1)
+
+    # Extract worktree name from path
+    worktree_name = current_wt.path.name
+
+    # Load forests
+    metadata = ctx.forest_ops.load_forests()
+
+    # Find forest for current worktree
+    forest = find_forest_by_worktree(metadata, worktree_name)
+
+    if forest is None:
+        user_output("Current worktree is not in a forest.")
+        raise SystemExit(0)
+
+    # Display forest
+    forest_header = click.style(f"Forest: {forest.name}", fg="cyan", bold=True)
+    count_text = f" ({len(forest.worktrees)} worktrees)"
+    user_output(forest_header + count_text)
+
+    # Display worktrees in tree format
+    for idx, wt in enumerate(forest.worktrees):
+        is_last = idx == len(forest.worktrees) - 1
+        prefix = "└──" if is_last else "├──"
+
+        # Highlight current worktree
+        wt_display = click.style(wt, fg="yellow")
+        branch_display = f"[{wt}]"
+
+        if wt == worktree_name:
+            indicator = click.style(" ← you are here", fg="bright_green", bold=True)
+            user_output(f"{prefix} {wt_display} {branch_display}{indicator}")
+        else:
+            user_output(f"{prefix} {wt_display} {branch_display}")