feat(client): authored NPC fallback line (§13)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/content/fallback/npc.json

@@ -0,0 +1,5 @@
+{
+  "npc": [
+    "The figure looks you over, says nothing you can use, and turns back to their work."
+  ]
+}

client/scripts/net/fallback_library.gd

@@ -1,37 +1,42 @@
 class_name FallbackLibrary
 extends RefCounted
-## Authored degraded-DM fallback text (charter §13). The client shows one of
-## these lines on ANY failure, in the Narrator's voice — never an error. If the
-## content file is missing or malformed the library returns a hardcoded
-## constant, so the fallback itself cannot fail.
+## Authored degraded-DM fallback text (charter §13). On ANY failure the client
+## shows one of these lines in-voice — never an error. Missing/malformed content
+## yields a hardcoded constant, so the fallback itself cannot fail.
 
 const PATH := "res://content/fallback/narrator.json"
+const NPC_PATH := "res://content/fallback/npc.json"
 const LAST_RESORT := "The chamber is cold. Something waits in the dark."
+const NPC_LAST_RESORT := "The figure regards you in silence, and the moment passes."
 
 var _lines: Array = []
+var _npc_lines: Array = []
 
 
-func _init(path := PATH) -> void:
-	_lines = _load(path)
+func _init(path := PATH, npc_path := NPC_PATH) -> void:
+	_lines = _load(path, "narrator")
+	_npc_lines = _load(npc_path, "npc")
 
 
 func narrator_line() -> String:
 	return str(_lines[0]) if not _lines.is_empty() else LAST_RESORT
 
 
-static func _load(path: String) -> Array:
+func npc_line() -> String:
+	return str(_npc_lines[0]) if not _npc_lines.is_empty() else NPC_LAST_RESORT
+
+
+static func _load(path: String, key: String) -> Array:
 	if not FileAccess.file_exists(path):
 		return []
 	var text := FileAccess.get_file_as_string(path)
-	# Use the instance API, not JSON.parse_string(): the static convenience
-	# method pushes an engine-level error on malformed input, which is noisy
-	# and (in this project's test config) turns a handled failure into a
-	# reported test error. The instance parse() just returns an Error code.
+	# Instance parse() (not JSON.parse_string) so malformed input returns an
+	# Error code instead of pushing an engine error the test config promotes.
 	var json := JSON.new()
 	if json.parse(text) != OK:
 		return []
 	var data = json.get_data()
 	if typeof(data) != TYPE_DICTIONARY:
 		return []
-	var lines = data.get("narrator", [])
+	var lines = data.get(key, [])
 	return lines if typeof(lines) == TYPE_ARRAY else []

client/tests/unit/test_fallback_library.gd

@@ -31,3 +31,15 @@ func test_empty_list_uses_last_resort():
 	f.close()
 	var lib = FallbackLibrary.new(path)
 	assert_eq(lib.narrator_line(), FallbackLibrary.LAST_RESORT)
+
+
+func test_npc_line_falls_back_to_constant_when_missing():
+	var lib = FallbackLibrary.new(
+		"res://content/fallback/does_not_exist.json",
+		"res://content/fallback/does_not_exist.json")
+	assert_eq(lib.npc_line(), FallbackLibrary.NPC_LAST_RESORT)
+
+
+func test_npc_line_reads_authored_file():
+	var lib = FallbackLibrary.new()  # default paths — real content
+	assert_ne(lib.npc_line(), "")