fix move language instruction to dynamic message to preserve prompt caching

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: krushnarout

app/pubspec.lock

@@ -253,10 +253,10 @@ packages:
     dependency: transitive
     description:
       name: characters
-      sha256: faf38497bda5ead2a8c7615f4f7939df04333478bf32e4173fcb06d428b5716b
+      sha256: f71061c654a3380576a52b451dd5532377954cf9dbd272a78fc8479606670803
       url: "https://pub.dev"
     source: hosted
-    version: "1.4.1"
+    version: "1.4.0"
   checked_yaml:
     dependency: transitive
     description:
@@ -1457,18 +1457,18 @@ packages:
     dependency: transitive
     description:
       name: matcher
-      sha256: "12956d0ad8390bbcc63ca2e1469c0619946ccb52809807067a7020d57e647aa6"
+      sha256: dc58c723c3c24bf8d3e2d3ad3f2f9d7bd9cf43ec6feaa64181775e60190153f2
       url: "https://pub.dev"
     source: hosted
-    version: "0.12.18"
+    version: "0.12.17"
   material_color_utilities:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "9c337007e82b1889149c82ed242ed1cb24a66044e30979c44912381e9be4c48b"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.13.0"
+    version: "0.11.1"
   mcumgr_flutter:
     dependency: "direct main"
     description:
@@ -2219,10 +2219,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "19a78f63e83d3a61f00826d09bc2f60e191bf3504183c001262be6ac75589fb8"
+      sha256: ab2726c1a94d3176a45960b6234466ec367179b87dd74f1611adb1f3b5fb9d55
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.8"
+    version: "0.7.7"
   time:
     dependency: transitive
     description:

backend/utils/llm/conversation_processing.py

@@ -641,8 +641,8 @@ def get_transcript_structure(
     response_language = output_language_code or language_code
 
     # First system message: task-specific instructions (static prefix enables cross-conversation caching)
+    # NOTE: language instructions are in context_message (second message) to keep this prefix fully static.
     instructions_text = '''You are an expert content analyzer. Your task is to analyze the provided content (which could be a transcript, a series of photo descriptions from a wearable camera, or both) and provide structure and clarity.
-    The content language is {language_code}. You MUST respond entirely in {response_language}.
 
     CRITICAL: If CALENDAR MEETING CONTEXT is provided with participant names, you MUST use those names:
     - The conversation DEFINITELY happened between the named participants
@@ -687,7 +687,7 @@ def get_transcript_structure(
     ).strip()
 
     # Second system message: conversation context (dynamic, per-conversation)
-    context_message = 'Content:\n{conversation_context}'
+    context_message = 'The content language is {language_code}. You MUST respond entirely in {response_language}.\n\nContent:\n{conversation_context}'
     prompt = ChatPromptTemplate.from_messages([('system', instructions_text), ('system', context_message)])
     chain = prompt | llm_medium_experiment.bind(prompt_cache_key="omi-transcript-structure") | parser