iOS accepts premature NDJSON EOF as success and leaves a permanent typing indicator #307

Summary

The iOS client treats an HTTP 200 NDJSON turn stream that reaches EOF without a terminal turn or error event as a successful turn. It persists the blank assistant placeholder, which continues rendering as an animated typing indicator even though streaming is false and the composer accepts another message.

Malformed NDJSON lines are also silently skipped, so a truncated/malformed stream can take the same false-success path.

Simulator reproduction

Tested on an iPhone 17 Pro simulator running iOS 26.5 with the current apps/ios/Graff sources, built into /tmp and launched with --autotest.

A controlled server returned:

1. 201 {"session_id":"clean-eof"} from POST /v1/sessions
2. HTTP 200 with an empty body from POST /v1/sessions/clean-eof

The mock received both requests. The app remained alive and re-enabled the composer, but left a blank assistant row displaying an indefinite typing animation with no error.

Root cause

GraffServeClient.streamTurn (apps/ios/Graff/Sources/GraffServeClient.swift:75-96) calls continuation.finish() after the line loop regardless of whether a terminal event was observed. Empty or undecodable lines are skipped.

ChatView.runTurn (ChatView.swift:119-150) creates a blank assistant placeholder before consuming the stream and treats clean completion as success. MessageBubble (ChatView.swift:220-237) decides to show TypingIndicator from message.text.isEmpty, not the actual streaming state.

Expected behavior

• Require exactly one valid terminal turn or error event before treating a turn as complete.
• Treat premature EOF or malformed protocol records as a transport/protocol failure.
• Remove or replace the blank placeholder on failure.
• Never show a typing indicator after the turn is no longer streaming.

Related

#285 covers thrown stream failures creating two assistant records. This is a separate clean-EOF/protocol-validation path where no error is thrown.