pkgs/clan: Add machine validator with suggestion logic

Add machine validator with suggestion logic to:
- `clan machines update`
- `clan machines delete`
- `clan machines update-hardware-config`

pkgs/clan-cli/clan_lib/machines/suggestions.py

@@ -0,0 +1,72 @@
+from clan_lib.errors import ClanError
+from clan_lib.flake import Flake
+
+
+def _levenshtein_distance(s1: str, s2: str) -> int:
+    """
+    Calculate the Levenshtein distance between two strings.
+    """
+    if len(s1) < len(s2):
+        return _levenshtein_distance(s2, s1)
+
+    if len(s2) == 0:
+        return len(s1)
+
+    previous_row = list(range(len(s2) + 1))
+    for i, c1 in enumerate(s1):
+        current_row = [i + 1]
+        for j, c2 in enumerate(s2):
+            insertions = previous_row[j + 1] + 1
+            deletions = current_row[j] + 1
+            substitutions = previous_row[j] + (c1 != c2)
+            current_row.append(min(insertions, deletions, substitutions))
+        previous_row = current_row
+
+    return previous_row[-1]
+
+
+def _suggest_similar_names(
+    target: str, candidates: list[str], max_suggestions: int = 3
+) -> list[str]:
+    if not candidates:
+        return []
+
+    distances = [
+        (candidate, _levenshtein_distance(target.lower(), candidate.lower()))
+        for candidate in candidates
+    ]
+
+    distances.sort(key=lambda x: (x[1], x[0]))
+
+    return [candidate for candidate, _ in distances[:max_suggestions]]
+
+
+def get_available_machines(flake: Flake) -> list[str]:
+    from clan_lib.machines.list import list_machines
+
+    machines = list_machines(flake)
+    return list(machines.keys())
+
+
+def validate_machine_names(machine_names: list[str], flake: Flake) -> None:
+    if not machine_names:
+        return
+
+    available_machines = get_available_machines(flake)
+    invalid_machines = [
+        name for name in machine_names if name not in available_machines
+    ]
+
+    if invalid_machines:
+        error_lines = []
+        for machine_name in invalid_machines:
+            suggestions = _suggest_similar_names(machine_name, available_machines)
+            if suggestions:
+                suggestion_text = f"Did you mean: {', '.join(suggestions)}?"
+            else:
+                suggestion_text = (
+                    f"Available machines: {', '.join(sorted(available_machines))}"
+                )
+            error_lines.append(f"Machine '{machine_name}' not found. {suggestion_text}")
+
+        raise ClanError("\n".join(error_lines))

pkgs/clan-cli/clan_lib/machines/test_suggestions.py

@@ -0,0 +1,82 @@
+from clan_lib.machines.suggestions import (
+    _levenshtein_distance,
+    _suggest_similar_names,
+)
+
+
+def test_identical_strings() -> None:
+    assert _levenshtein_distance("hello", "hello") == 0
+
+
+def test_empty_string() -> None:
+    assert _levenshtein_distance("", "") == 0
+    assert _levenshtein_distance("hello", "") == 5
+    assert _levenshtein_distance("", "world") == 5
+
+
+def test_single_character_difference() -> None:
+    assert _levenshtein_distance("hello", "hallo") == 1  # substitution
+    assert _levenshtein_distance("hello", "helloo") == 1  # insertion
+    assert _levenshtein_distance("hello", "hell") == 1  # deletion
+
+
+def test_multiple_differences() -> None:
+    assert _levenshtein_distance("kitten", "sitting") == 3
+    assert _levenshtein_distance("saturday", "sunday") == 3
+
+
+def test_case_sensitivity() -> None:
+    assert _levenshtein_distance("Hello", "hello") == 1
+    assert _levenshtein_distance("HELLO", "hello") == 5
+
+
+def test_exact_match() -> None:
+    candidates = ["machine1", "machine2", "machine3"]
+    suggestions = _suggest_similar_names("machine1", candidates)
+    assert suggestions[0] == "machine1"
+
+
+def test_close_match() -> None:
+    candidates = ["machine1", "machine2", "machine3"]
+    suggestions = _suggest_similar_names("machne1", candidates)  # missing 'i'
+    assert "machine1" in suggestions[:2]
+
+
+def test_case_insensitive_matching() -> None:
+    candidates = ["Machine1", "MACHINE2", "machine3"]
+    suggestions = _suggest_similar_names("machine1", candidates)
+    assert "Machine1" in suggestions[:2]
+
+
+def test_max_suggestions_limit() -> None:
+    candidates = ["aa", "ab", "ac", "ad", "ae"]
+    suggestions = _suggest_similar_names("a", candidates, max_suggestions=3)
+    assert len(suggestions) <= 3
+
+
+def test_empty_candidates() -> None:
+    suggestions = _suggest_similar_names("test", [])
+    assert suggestions == []
+
+
+def test_realistic_machine_names() -> None:
+    candidates = ["web-server", "database", "worker-01", "worker-02", "api-gateway"]
+
+    # Test typo in web-server
+    suggestions = _suggest_similar_names("web-sever", candidates)
+    assert suggestions[0] == "web-server"
+
+    # Test partial match
+    suggestions = _suggest_similar_names("work", candidates)
+    worker_suggestions = [s for s in suggestions if "worker" in s]
+    assert len(worker_suggestions) >= 2
+
+
+def test_sorting_by_distance_then_alphabetically() -> None:
+    candidates = ["zebra", "apple", "apricot"]
+    suggestions = _suggest_similar_names("app", candidates)
+    # Both "apple" and "apricot" have same distance (2),
+    # but "apple" should come first alphabetically
+    apple_index = suggestions.index("apple")
+    apricot_index = suggestions.index("apricot")
+    assert apple_index < apricot_index