refactor: name recovery boundaries and compact IR strings

source/lower/lower.hon

@@ -560,8 +560,17 @@ lower_string proc(state @mut State, id ast.NodeId) ir.ValueId ! (mem.AllocError
         trap(state, try diagnostics.add(state.diagnostics, .invalid_escape, span), span)
         return ir.no_value
     }
-    # retain the complete allocation for freeing, but expose only decoded bytes.
-    try arraylist.append(&state.module.strings, owned)
+    if (state.module.strings.items.len > usize(maxval!(ir.StringId)))
+        return .out_of_memory
+
+    string_id :: ir.StringId(state.module.strings.items.len)
+    try arraylist.append(&state.module.strings, ir.StringStorage{
+        allocation = owned,
+        len = length,
+    })
     transferred = true
-    return try constant(state, ir.Value{ type = .string, data = ir.ValueData{ string = owned[..length] } }, span)
-}
+    return try constant(state, ir.Value{
+        type = .string,
+        data = ir.ValueData{ string = string_id },
+    }, span)
+}

source/lower/lower.test.hon

@@ -91,7 +91,20 @@ owns_decoded_strings_after_source_and_frontend_are_freed test {
     outcome :: try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
     try testing.expect(outcome.trap == null)
     try testing.expect_equal(ir.Type.string, outcome.value.type)
-    try testing.expect(mem.eql(outcome.value.data.string, "a\\\"\n\r\t\x00Az"))
+    try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.string), "a\\\"\n\r\t\x00Az"))
+}
+
+resolves_module_local_string_ids_after_frontend_cleanup test {
+    diagnostic_store := diagnostics.init(mem.c_allocator)
+    defer diagnostics.deinit(&diagnostic_store)
+    module := try compile_owned(
+        "first :: \"not the result\"\nidentity proc(value string) string { return value }\nmain proc() string { return identity(\"second\\n\\x00\") }\n",
+        &diagnostic_store,
+    )
+    defer ir.deinit(&module)
+    outcome :: try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
+    try testing.expect(outcome.trap == null)
+    try testing.expect_equal([]u8, "second\n\x00", ir.string_bytes(&module, outcome.value.data.string))
 }
 
 honors_float_context_and_float_division test {