Sealed moves
A sealed move is a value one player commits to (a move, a word, a number) that the other players may not read until the mini app reveals it, and that its owner cannot change after committing. The Rock Paper Scissors mini app of the Localix marketplace is the reference. A word-guessing game, where one agent picks the word and the user or other agents guess, uses the same three parts.
Terminology
| Term | Meaning | Boundary |
|---|---|---|
| Sealed | A committed value with its salt and digest, kept whole by the mini app backend. | Never sent to anyone but its owner before the reveal. |
| Digest | Hex SHA-256 of salt:value. | Shown before the reveal; proves nothing was swapped. |
| View | What one audience may see of a commitment: the digest, or everything. | Built per audience by the mini app, e.g. viewFor(game, viewer). |
| Sealed key | A tool input field the host withholds from storage and from clients. | The calling model keeps the real value for the rest of its run. |
What you can do
| Task | Mechanism | Boundary |
|---|---|---|
| Let the agent commit without the user seeing | presentation: { sealed: { input: ['move'] } } on the tool | Top-level input keys only. The chat shows [sealed] in their place. |
| Withhold a tool's whole result | presentation: { sealed: { result: true } } | Also withholds details, so an offered view link is lost. Prefer results that never name it. |
| Commit to a value | seal(value, owner, at) from @localixai/mini-app-sdk/backend | Values are strings. A fresh 16-byte salt each time. |
| Show another audience the commitment | sealedView(sealed) from @localixai/mini-app-sdk/sealed | The digest only, until revealSealed(sealed, at). |
| Let the user check the reveal | verifySealed(view) in the browser | WebCrypto; false for an unrevealed or tampered view. |
How it works
- The agent calls the mini app's tool with the secret in a sealed key. The host replaces the key
with
[sealed]in the tool item before the first copy is persisted or streamed. That is the accumulator funnel that already shields credentials, so every copy is covered: streamed arguments, progress, the result and a failed call's error. - The tool seals the value (
seal) and keeps the whole record in its own storage. The tool result must not name the value: results are shown to the user. - Every route answer, wake message and published chat context is built from a per-audience view
that carries
sealedView(...)for anything the audience may not read. - When the game's rule says so, the mini app calls
revealSealed. From then on the view carries the value and salt, andverifySealedlets the user's own browser confirm the digest.
Subagents
A subagent's tool calls and results stay in its own session: its parent reads only its final report.
A secret in a sealed key therefore reaches neither the user nor the parent through the subagent's
history. The mini app can tell agents apart through the tool context's session.agent.agentId and
pass it to seal as the owner.
What it does not hide
- The model's own text and reasoning stream to the user. The mini app's guide must tell the agent not to deliberate or hint in writing, and a sealed move that answers a wake should end the turn.
- After the run, the author's own history holds
[sealed]too. A game that needs the secret on a later turn returns it through a tool whose result is sealed (result: true) or keeps the agent from needing it. - Mini app storage is ordinary files in the chat's session folder on the user's machine.