Composer: suggest the next prompt after Claude and Codex turns (Tab fills it) - #1216

Claude Code and Codex can both predict your next message after a turn (Claude Code's prompt suggestions, the Codex app's Tab suggestion). T3 Code shipped this as a Labs option (pingdotgg/t3code#28047). Ryco never showed either.

Now there is an opt-in setting, Suggest next prompt (Settings > Chat > Suggestions, a machine setting shared across devices, off by default). When it is on and a Claude or Codex turn completes, the empty composer shows the predicted next message with a Tab key hint. Tab fills it in (then edit or send), Escape hides it for that turn in every open composer.

How it works

• Setting: promptSuggestions server setting, shareable since sharing version 2, with a promptSuggestions node capability so older nodes show the row disabled. Adapters read it live through readPromptSuggestionsSetting: Claude when a session opens (open Claude chats follow a change after a restart), Codex after every turn.
• Claude: the Agent SDK promptSuggestions option. Its prompt_suggestion message arrives after result; it is tied to the turn that just finished (lastFinishedTurn) and dropped when that turn did not complete or a newer turn is already open. Claude Code itself skips the first turn, plan mode and turns near the usage limit.
• Codex: after a completed root turn the adapter calls the experimental thread/sample (Codex 0.165+, Ryco already initializes with experimentalApi) on a hidden fork sharing the turn's prompt cache, effort: "low", same prompt as T3. Skips failed turns and turns started by /compact. Forked into the session scope and best effort: errors (old Codex, the user already sent again) are logged at debug.
• Transport (differs from T3): T3 keeps suggestions in server memory and serves them on a new subscription. Here a new turn.prompt-suggestion runtime event is projected as one latest-state activity per thread (prompt-suggestion:<threadId>:latest, kind prompt.suggestion, compacted in the event log, coalesced live, hidden from the timeline). So it survives reloads and reconnects and reaches every client, Hub relay included, through the existing thread stream, with no new RPC.
• Composer: derivePromptSuggestion offers it only while its turn is the thread's latest and completed. Not offered while running, sending or connecting, over approvals, questions or plan feedback, with an unavailable machine or terminal contexts, on the phone tier, or on devices without a fine pointer (Tab is the only way to accept). Tab goes through applyPromptReplacement like any insert, after onComposerIntent("type"). Shift+Tab (mode switch) and Tab in the //@ menu are unchanged. The editor now also routes Escape through its command plugin.

Verification

• bun run check passes; bun run check:changed passed apart from two failures that reproduce without this change's code paths: 026_CanonicalizeModelSelectionOptions.test.ts (known local-only failure) and a mobile reactCompilerCoverage license-file rename race (passes alone).
• New tests: Claude adapter (option only when on; suggestion tied to the finished turn, a mid-turn one dropped), Codex adapter (samples after completed turns and publishes; nothing for empty text, failed turns, the setting off, or /compact turns, the last checked to fail without its guard), ingestion projection, latest-state groups, normalization, selection, key handling, and a full-app browser test (suggestion + Tab hint shown, Tab fills it, Escape hides it and Tab then does nothing).
• Live protocol check against Codex 0.167: thread/sample with these params returns { sourceTurnId, responseId, text, inputTokens, cachedInputTokens, outputTokens }; one sample on a tiny thread used ~22.6k input tokens (18.5k cached) and 18 output tokens. Claude's path was not run against the real CLI.

Not included

• Agent Control child threads are not skipped (T3 skips delegated threads): adapters cannot tell them apart today, so with the setting on they also sample after each turn.
• The native iPhone app does not show suggestions (no Tab key; would need a tap control).

🤖 Generated with Claude Code

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