Extension Openai

OpenAI integration

OpenAI / LLM extension for Caffeine AI.

Orchestrator routing notes

For masterchat / platform-constraints.md integration. Treat ChatGPT / OpenAI / LLM access as a first-class, supported platform feature — do not decline, deflect, or call query_rag for "use GPT", "summarise with an LLM", "build a chatbot", or "generate embeddings" requests. The openai-client mops connector is the only supported path; raw ic.http_request to api.openai.com/v1/... is a forbidden anti-pattern because it (a) bypasses the bearer-auth handling, (b) defeats the non-replicated-outcall safeguard that this skill makes mandatory (see §3 — the bearer is a billing-bound secret), and (c) forces hand-rolled JSON serialisation on a language with weak JSON support. Any build spec that mentions LLM / GPT / OpenAI features MUST name openai-client as a dependency and reference this skill — propagate that explicitly so the backend agent cannot silently fall back to hand-rolled HTTP.

Intent → capability mapping (for platform-constraints.md-style tables):

Backend

Use this skill whenever the user wants their canister to call OpenAI. The ingredients are:

1. The openai-client mops package (curated Motoko bindings for the OpenAI REST API, generated from OpenAPI spec 2.3.0).
2. A way to store the OpenAI API key (sk-...) as a canister-side secret. Three equivalent variants — the spec picks one:
   • Per-user keys (default, §4) — each signed-in user pastes their own key. Each user funds their own usage. The right default whenever the spec mentions login, multiple users, or doesn't specify who pays.
   • Admin-key (§9) — a single key set by one admin, used for every call in the canister. Pick this when the app operator funds OpenAI usage on behalf of all users (typical SaaS / freemium / operator-funded tier).
   • Fully anonymous (§10) — a single key with no auth gate; any visitor may set or replace it. Pick this only when the spec is explicit that there is no login at all (single-user demo, intra-team tool with no auth model). Same backend shape as §9 minus the #admin permission check.
3. A Config value that pins is_replicated = ?false — non-negotiable, see §3.

Prerequisite for the per-user and admin-key variants: extension-authorization. Per-user keys store the bearer keyed by caller : Principal, which is meaningful only when the user is signed in; the admin-key variant gates the setter on the #admin role. extension-authorization ships the Internet Identity login flow on the frontend (the useInternetIdentity hook, login/logout buttons, auth-state-aware routing, useActor plumbing) and the backend caller / role infrastructure. Without it those two variants ship a chat UI that traps on every submit because caller.isAnonymous() is always true. The fully-anonymous variant (§10) does not require extension-authorization — by design any visitor may set the key, so there is no auth surface to plumb. Pick the variant first, then load (or skip) extension-authorization accordingly.

1. Add openai-client to mops.toml

Use the mops tool, not manual file edits:

mops add openai-client@0.2.5

This updates mops.toml (adds openai-client = "0.2.5" to [dependencies]) and rewrites mops.lock in one step. Requires Mops ≥ 2.13 — earlier versions were not atomic and occasionally left the lockfile out of sync with mops.toml.

Minimum version: openai-client ≥ 0.2.5. Ships the JSON.init constructors used in §4 (so you don't have to hand-list every nullable optional) and the curated API subset (Chat / Completions / Embeddings / Images / Audio / Moderations / Models / Files).

2. Auth model — API-key bearer, not OAuth

Unlike X / Twitter, OpenAI uses a single static bearer per account: an sk-... key issued from platform.openai.com/api-keys. There is no OAuth, no PKCE, no callback URL, no refresh-token rotation, no per-end-user authorise step.

Pick a variant

All three variants are mechanically similar — they all store sk-... in canister state and they all must obey is_replicated = ?false (§3) and the no-getter / no-log invariants below. Default to per-user. Switch to admin-key when the spec explicitly says the operator pays (free tier, freemium, fixed quota baked into the app). Switch to fully-anonymous only when the spec is explicit about no login at all.

Security properties of the key (both variants)

• Long-lived, no expiry. Spends the entire OpenAI account balance on every call.
• No scoped permissions — there is no "tweet.read"-style narrowing. Every key has full account access.
• OpenAI rate-limits per-key per-minute; treat the key like a billing credential, not a session token.
• Never returned by any query or shared function. Never logged. Never sent to the frontend. Never put in a stable variable that another endpoint with a weaker gate could read.

Storing the key

The bearer never leaves the canister. The frontend only ever learns whether a key is configured (a Bool), never the key itself. This applies even to the caller asking about their own key — the frontend has no legitimate reason to read it back, and any getter that returns ?Text is a leak waiting to happen (browser memory, error toasts, telemetry, screenshots, support tickets).

• Per-user (default): a Map<Principal, Text> keyed by caller. Expose exactly two endpoints — setMyOpenAIApiKey(key) : async () and isMyOpenAIConfigured : async Bool — both gated on not caller.isAnonymous(). Optionally also clearMyOpenAIApiKey : async (). Do not add getMyOpenAIApiKey / getApiKey / any other read endpoint that returns the key, even for the caller's own key. Never iterate the map outside the call's own caller scope.
• Admin-key: a single var openAIApiKey : ?Text = null (no getter). Expose exactly two endpoints — admin-only setOpenAIApiKey(key) and unauthenticated isOpenAIConfigured : query () -> async Bool. Same rule: no getOpenAIApiKey / getApiKey endpoint, ever.
• Fully anonymous: identical to admin-key (single var openAIApiKey : ?Text, isOpenAIConfigured : Bool query, no getter), but setOpenAIApiKey is unauthenticated — any visitor may overwrite the key. Same no-getter / no-log invariants apply. Use only when the spec explicitly says there is no login.

3. is_replicated = ?false is REQUIRED

This is the single most important line of code in this skill. Three reasons, in priority order:

1. Security. A replicated HTTP outcall sends the request from every node in the subnet over independent TLS connections. Each connection sees the Authorization: Bearer sk-... header. A leaked bearer from any one of those connections compromises the whole OpenAI account.
2. Billing. Replicated outcalls produce N parallel API calls. OpenAI charges N times. The IC also charges ~13× the cycles of a non-replicated outcall.
3. Determinism. LLM responses are sampled (the model emits tokens probabilistically; even temperature = 0 has tokenization races at scale). Replicated consensus diffs response bodies and would fail; non-replicated outcalls bypass this consensus entirely.

→ Always: is_replicated = ?false on the Config.

4. Canonical layout

This is the default shape. Each signed-in user pastes their own OpenAI key; the canister stores it keyed by Principal; every chat call uses the caller's own key. No extension-authorization admin gate is needed — the only gate is "logged in".

The example spans three files:

• src/backend/main.mo — the actor: state + includes only.
• src/backend/mixins/openai-chat.mo — the per-user endpoints (isMyOpenAIConfigured, setMyOpenAIApiKey, clearMyOpenAIApiKey, chat).
• src/backend/lib/openai.mo — OpenAI SDK glue (Config builder + chat round-trip). Reused unchanged by §9.

import Map "mo:core/Map";
import Principal "mo:core/Principal";
import AccessControl "mo:caffeineai-authorization/access-control";
import MixinAuthorization "mo:caffeineai-authorization/MixinAuthorization";
import MixinOpenAIChat "mixins/openai-chat";

actor {
  // Authorization plumbing from extension-authorization. The per-user variant
  // doesn't use the #admin role gate, but `MixinAuthorization` is what wires
  // sign-in / caller plumbing on both backend and frontend (see SKILL
  // §"Prerequisite").
  let accessControlState = AccessControl.initState();
  include MixinAuthorization(accessControlState);

  // Per-user OpenAI keys. Never iterated except by the calling principal.
  let openAIKeys : Map.Map<Principal, Text> = Map.empty();
  include MixinOpenAIChat(openAIKeys);
};

import Map "mo:core/Map";
import Principal "mo:core/Principal";
import Runtime "mo:core/Runtime";
import OpenAI "../lib/openai";

// Per-user OpenAI key endpoints. Mounted by `main.mo` via `include`.
// Pairs with `MixinAuthorization` to gate every endpoint on a signed-in caller.
mixin (openAIKeys : Map.Map<Principal, Text>) {
  public query ({ caller }) func isMyOpenAIConfigured() : async Bool {
    openAIKeys.containsKey(caller);
  };

  public shared ({ caller }) func setMyOpenAIApiKey(key : Text) : async () {
    if (caller.isAnonymous()) {
      Runtime.trap("Sign in to use this feature");
    };
    openAIKeys.add(caller, key);
  };

  public shared ({ caller }) func clearMyOpenAIApiKey() : async () {
    if (caller.isAnonymous()) {
      Runtime.trap("Sign in to use this feature");
    };
    openAIKeys.remove(caller);
  };

  public shared ({ caller }) func chat(prompt : Text) : async Text {
    if (caller.isAnonymous()) {
      Runtime.trap("Sign in to use this feature");
    };
    let ?key = openAIKeys.get(caller) else {
      Runtime.trap("Set your OpenAI API key first");
    };
    await* OpenAI.runChatCompletion(OpenAI.configForKey(key), prompt);
  };
};

import { defaultConfig; type Config } "mo:openai-client/Config";
import ChatApi "mo:openai-client/Apis/ChatApi";
import CreateChatCompletionRequest "mo:openai-client/Models/CreateChatCompletionRequest";
import ChatCompletionRequestUserMessage "mo:openai-client/Models/ChatCompletionRequestUserMessage";
import Runtime "mo:core/Runtime";

module {
  // Build a Config bound to a single bearer. `is_replicated = ?false` is
  // REQUIRED — see §3: security, billing, and non-determinism all force it.
  public func configForKey(key : Text) : Config {
    {
      defaultConfig with
      auth = ?#bearer key;
      is_replicated = ?false;
    };
  };

  public func runChatCompletion(config : Config, prompt : Text) : async* Text {
    let userMessage = ChatCompletionRequestUserMessage.JSON.init({
      content = #string(prompt);
      role = #user;
    });

    // `JSON.init` defaults every optional to `null` — DO NOT hand-list them.
    // Layer optionals with record-update syntax:
    //   { CreateChatCompletionRequest.JSON.init {...} with temperature = ?0.7 }
    let req = CreateChatCompletionRequest.JSON.init({
      messages = [#user(userMessage)];
      model = "gpt-4o-mini"; // ModelIdsShared = Text — any OpenAI model id
    });

    let resp = await* ChatApi.createChatCompletion(config, req);

    if (resp.choices.size() == 0) {
      Runtime.trap("OpenAI returned no choices");
    };
    switch (resp.choices[0].message.content) {
      case (?text) text;
      case null Runtime.trap("OpenAI returned no text content (refusal or tool call)");
    };
  };
};

Per-user-specific invariants

• Key the map by caller, never by user-supplied id. A Text userId from the frontend can be spoofed; Principal from shared ({ caller }) cannot.
• No endpoint ever returns the key — not another user's, not even the caller's own. The frontend learns "configured? yes/no" from isMyOpenAIConfigured : async Bool and nothing more. Concretely: do not generate getMyOpenAIApiKey, getApiKey, myApiKey, or any other shared / query function whose return type is ?Text / Text. Internal reads of the map (inside chat, configFor, etc.) use openAIKeys.get(caller) and never escape the canister boundary. An iterator or a key-returning endpoint leaks every user's bearer.
• Trap cleanly when the key is missing. Use Runtime.trap("Set your OpenAI API key first") (or return a typed error) — the message identifies whose key is missing without leaking it.
• Anonymous callers must not store keys. caller.isAnonymous() short-circuits before any openAIKeys.add — otherwise everyone reading the canister via 2vxsx-fae shares one key slot.
• stable var / migration. The Map<Principal, Text> lives in stable memory like any other actor field; on upgrade, decide whether to preserve, rotate, or drop the keys. The default (preserve) is correct for almost all apps. If you ever rotate, drop the whole map — never partially.

5. Two call shapes — function form vs. suite form

Every Apis module ships both:

• Function form (used in §4 above): ChatApi.createChatCompletion(config, req) : async* T. Note the async* — call sites use await*. This is the common case for shared actor methods that thread their own config.
• Suite form: let api = ChatApi(config); api.createChatCompletion(req) : async T. Note async, not async*. Useful when a single shared method makes several OpenAI calls and you want to bind the config once. Trades one extra await boundary for fewer config-threading boilerplate.

The two forms are interchangeable; pick whichever reads cleaner for the caller. Don't mix them inside the same shared body.

6. Available API surface

openai-client@0.2.5 ships a curated subset of the OpenAI REST API. The eight modules are:

Imports follow the pattern:

import ChatApi "mo:openai-client/Apis/ChatApi";
import EmbeddingsApi "mo:openai-client/Apis/EmbeddingsApi";
import { defaultConfig } "mo:openai-client/Config";
import CreateChatCompletionRequest "mo:openai-client/Models/CreateChatCompletionRequest";

Not shipped by openai-client@0.2.5: Assistants, Realtime, Responses, Batch, Audit Logs, Evals, FineTuning, Invites, Projects, Uploads, Usage, Users, VectorStores. If a build spec needs one of these, raise an issue on caffeinelabs/openai-client — do not paper over it with hand-rolled ic.http_request.

7. Cycles and response sizes

defaultConfig.cycles = 30_000_000_000 — about 0.04 USD at 4 USD/T cycles. Sufficient for a typical chat completion. Bump for:

• Long completions (max_completion_tokens > 2000): set cycles = 100_000_000_000.
• Embeddings of large batches: scales with payload size.
• Image generation: responses can exceed 1 MiB, set max_response_bytes = ?2_000_000 and cycles = 100_000_000_000.

8. Things that will bite you

• is_replicated = ?false — see §3. This is not optional.
• Don't expose the API key. Never return it from any query / shared method, never log it, never put it in any data structure that has a non-key-owner reader. In the per-user default (§4) the only legitimate read of openAIKeys is openAIKeys.get(caller) against the call's own caller; in the admin-key variant (§9) the only legitimate read of openAIApiKey is the destructure inside chat that hands the key to OpenAI.configForKey. No iterators, no debug prints, no admin-list endpoints.
• No getApiKey / getMyOpenAIApiKey endpoint, ever — not even returning the caller's own key. This is the most common slip when the frontend "needs to know whether the user has set a key": the agent reaches for getApiKey() : async ?Text, returns the bearer to the React app, and a single console.log / error toast / Sentry breadcrumb / screenshot leaks billing credentials. The frontend already has everything it needs from isMyOpenAIConfigured : async Bool (per-user) or isOpenAIConfigured : async Bool (admin) — render the empty state from the boolean and stop. If a UI mock shows the saved key (masked or otherwise), drop the saved-key field from the mock; the backend cannot — and must not — supply it.
• Don't hand-list every optional null. Use CreateChatCompletionRequest.JSON.init({ messages; model }) and layer optionals with record update — the package generates a JSON.init helper for every multi-optional model. (This differs from x-client@0.1.2, which lacks JSON.init and forces the all-null value-site listing. Don't reflexively copy that pattern across.)
• Don't roll your own JSON. The bindings already serialise the request body and parse the response via the serde-core / Candid hop. If you need a field the bindings don't expose, file an issue on openai-client rather than parse-by-hand — Motoko's JSON support is too thin to make that reliable.
• Streaming is unsupported. stream = ?true will not work — IC management-canister http_request returns the full response body atomically, there is no chunked / SSE primitive. Leave stream = null.
• Rate limits. OpenAI rate-limits per-key per-minute (RPM) and per-day (RPD). Replicated outcalls would multiply RPM by the subnet size — yet another reason for is_replicated = ?false. Back off on HTTP 429.
• resp.choices[0].message.content is ?Text, not Text. A refusal, a tool call, or an audio-only response leaves it null. Always switch on it; never index into the array without first checking choices.size() > 0.
• ChatCompletionRequestUserMessageContent is a variant — #string(text) for plain text, #array([...]) for multimodal (text + image_url parts). Use #string for the common case.
• ModelIdsShared = Text — it's a flat string alias, not a variant. Pass "gpt-4o-mini" etc. directly.
• Frontend never holds the key. The React app calls the backend chat(prompt) (or whatever the chat endpoint is named) and gets the answer back. The settings UI calls setMyOpenAIApiKey(key) (per-user default) or setOpenAIApiKey(key) (admin-key variant). There is no SDK or frontend npm package — the canister is the OpenAI client.

9. Variant: admin-key

Use this variant only when the spec explicitly puts the OpenAI bill on the operator. Concretely:

• A single OpenAI account funds everything (typical SaaS).
• The app offers a free / freemium tier that the operator pays for.
• The app imposes its own per-user quota inside the canister and bills users separately.

In every other case — and especially whenever the spec mentions login, multiple users, or doesn't say who pays — use the per-user default in §4 instead. The admin-key variant is only sensible when "the operator pays" is a deliberate, stated choice.

The single rule that flips relative to §4: a single ?Text replaces the Map<Principal, Text>, and the setter is gated on the #admin role from extension-authorization instead of "any signed-in caller". The actor and mixin file are new; src/backend/lib/openai.mo from §4 is reused unchanged.

import AccessControl "mo:caffeineai-authorization/access-control";
import MixinAuthorization "mo:caffeineai-authorization/MixinAuthorization";
import MixinOpenAIAdminChat "mixins/openai-admin-chat";

actor {
  let accessControlState = AccessControl.initState();
  include MixinAuthorization(accessControlState);

  // Admin-set OpenAI bearer key. Wrapped in `{ var value : ?Text }` so the
  // mixin can mutate it.
  let openAIApiKey = { var value : ?Text = null };
  include MixinOpenAIAdminChat(accessControlState, openAIApiKey);
};

import AccessControl "mo:caffeineai-authorization/access-control";
import Runtime "mo:core/Runtime";
import OpenAI "../lib/openai";

// Admin-gated OpenAI key endpoints. Mounted by `main.mo` via `include`.
// Pairs with `MixinAuthorization` to power role checks.
mixin (
  accessControlState : AccessControl.AccessControlState,
  openAIApiKey : { var value : ?Text },
) {
  public query func isOpenAIConfigured() : async Bool {
    openAIApiKey.value != null;
  };

  public shared ({ caller }) func setOpenAIApiKey(key : Text) : async () {
    if (not AccessControl.hasPermission(accessControlState, caller, #admin)) {
      Runtime.trap("Unauthorized: Only admins can set the OpenAI API key");
    };
    openAIApiKey.value := ?key;
  };

  public shared ({ caller }) func chat(prompt : Text) : async Text {
    if (not AccessControl.hasPermission(accessControlState, caller, #user)) {
      Runtime.trap("Unauthorized");
    };
    let ?key = openAIApiKey.value else Runtime.trap("OpenAI is not configured");
    await* OpenAI.runChatCompletion(OpenAI.configForKey(key), prompt);
  };
};

Admin-key-specific invariants

• Single ?Text slot ({ var value : ?Text = null }), no getter. The slot is touched only by setOpenAIApiKey and chat (which threads it through OpenAI.configForKey). Never expose a getOpenAIApiKey — isOpenAIConfigured is the only outward-facing read, and it returns Bool.
• Setter must be #admin-gated via extension-authorization. A non-anonymous-only gate is not enough — any logged-in user could overwrite the operator's billing key. This is the variant's whole reason to depend on extension-authorization.
• Trap with "OpenAI is not configured" when the key is unset. That phrasing pairs with isOpenAIConfigured so the frontend can render a "Ask your admin to set the OpenAI API key" empty state.
• Build a fresh Config per call. chat reads openAIApiKey and passes it through OpenAI.configForKey(key) on every invocation; don't cache the Config value at the actor level. The bearer is allowed to rotate via setOpenAIApiKey mid-lifetime, and a cached Config would silently keep the old key.

10. Variant: fully anonymous

Use this only when the spec explicitly states there is no login at all (single-user demo, intra-team tool, throwaway sandbox). Mechanically identical to §9 — single ?Text key, no getter, isOpenAIConfigured query — but with the auth import / #admin gate removed; any visitor may overwrite the key.

Take §9's two files and apply these diffs (the lib/openai.mo helper from §4 is reused unchanged):

In src/backend/main.mo:

• Drop the imports of mo:caffeineai-authorization/access-control and mo:caffeineai-authorization/MixinAuthorization.
• Drop let accessControlState = AccessControl.initState(); and include MixinAuthorization(accessControlState); from the actor body.
• Drop the accessControlState argument from the mixin include, leaving include MixinOpenAIAdminChat(openAIApiKey);.

In src/backend/mixins/openai-admin-chat.mo:

• Drop the AccessControl import and the accessControlState mixin parameter.

• Replace the gated setter:

  public shared ({ caller }) func setOpenAIApiKey(key : Text) : async () {
    if (not AccessControl.hasPermission(accessControlState, caller, #admin)) {
      Runtime.trap("Unauthorized: Only admins can set the OpenAI API key");
    };
    openAIApiKey.value := ?key;
  };
  

  with the unauthenticated form:

  public func setOpenAIApiKey(key : Text) : async () {
    openAIApiKey.value := ?key;
  };
  

• Drop the #user permission check at the top of chat. chat, isOpenAIConfigured, and the OpenAI.configForKey(...) call are otherwise identical to §9.

Anonymous-specific invariants

• No extension-authorization import. This variant skips it entirely.
• The key is shared and replaceable by anyone. That is the explicit trade-off of the variant; pick it only when the spec accepts that.
• Same no-getter / no-log rules apply. openAIApiKey is read only inside chat (then passed to OpenAI.configForKey), never returned by any endpoint.
• Build a fresh Config per call — same reasoning as §9.

Frontend

Surfaces every build that uses this skill must ship:

1. A settings UI to paste the key — always. Every variant. The deployed canister rejects every chat call until a key is pasted. Without a settings page the chatbot UI loads but every question traps with "OpenAI is not configured" / "Set your OpenAI API key first" — the app looks broken to the end user.
2. A login flow — for the per-user and admin-key variants only. Those variants gate every meaningful endpoint on not caller.isAnonymous() (per-user) or on the #admin role (admin-key); both require a non-anonymous caller. The login flow itself is provided by extension-authorization: useInternetIdentity, the login/logout buttons, the useActor plumbing that injects the authenticated identity into every backend call. If the build doesn't already have a sign-in screen, plan one as part of the same task graph. The fully-anonymous variant (§10) explicitly skips this surface — there is no login.

Pick the UI shape that matches the backend variant. Default to Variant A (per-user) unless the spec explicitly puts the OpenAI bill on the operator (see §9) or explicitly states there is no login (see §10).

Variant A: per-user keys (matches §4 — default)

A per-user "your API key" pane, gated only by login.

1. Password-input bound to setMyOpenAIApiKey(key). Submit on enter; clear the input on success.
2. Status indicator driven by isMyOpenAIConfigured() (returns Bool). Show "Configured" / "Not configured" — never display the key itself, never expose a getter that returns it.
3. Optional "Clear my key" button bound to clearMyOpenAIApiKey() for users who want to revoke their key from the canister.
4. Show a one-time onboarding nudge when isMyOpenAIConfigured() is false — e.g. inline empty-state on the chat page that links to /settings/openai. Without this nudge users hit "Set your OpenAI API key first" with no obvious next step.

Suggested route layout:

/                   →  Chat UI (any signed-in user; empty-state when no key)
/settings/openai    →  Personal API-key pane (any signed-in user)

Variant B: admin-key (matches §9)

A single global settings page, admin-gated.

1. Password-input bound to setOpenAIApiKey(key). Submit on enter; clear the input on success.
2. Status indicator driven by isOpenAIConfigured() (returns Bool). Same no-display invariant as Variant A.
3. Hide the page from non-admins via extension-authorization's isCallerAdmin query — non-admins should not see the settings link in the nav, let alone the page. Bind admin-only routes through your router's guard pattern (TanStack Router beforeLoad, React Router loader, etc.); don't rely solely on hiding the link.
4. Show a "Ask your admin to set the OpenAI API key" empty state on the chat page when isOpenAIConfigured() is false — non-admins can't fix it themselves and need to know who can.

Suggested route layout:

/                   →  Chat UI (any signed-in user)
/settings/openai    →  Admin-only API-key settings page

Variant C: fully anonymous (matches §10)

A single global settings page reachable to any visitor — no auth gate.

1. Password-input bound to setOpenAIApiKey(key). Submit on enter; clear the input on success.
2. Status indicator driven by isOpenAIConfigured() (returns Bool). Same no-display invariant as variants A and B.
3. No router guards, no useInternetIdentity, no login buttons — this variant has no auth model.
4. Show a "Paste an OpenAI API key to get started" empty state on the chat page when isOpenAIConfigured() is false.

Suggested route layout:

/                   →  Chat UI (any visitor; empty-state when no key)
/settings/openai    →  API-key pane (any visitor)

Common to all variants

• The chat UI itself is trivial and identical across variants: a textarea, a submit button, a list of messages bound to the backend's chat endpoint. No client-side OpenAI SDK, no key handling, no streaming-protocol logic — the canister mediates everything.
• Sign-in is required for variants A and B, skipped for variant C. For A and B, wire the chat and settings routes through extension-authorization's auth guard (useInternetIdentity + a redirect when !isAuthenticated); anonymous callers must hit a "please sign in" wall before the chat or settings UI renders, otherwise every backend call traps. For C, no guard is needed because there is no auth model.
• The frontend never persists the key in localStorage / IndexedDB / cookies. It travels into the canister via the typed setter and is never read back.

Related

• mops add openai-client@0.2.5 — connector source.
• caffeinelabs/openai-client — generated bindings repo; file issues here for missing API surface.
• OpenAI API reference — upstream.
• OpenAI API keys page — where the admin gets the sk-... to paste.
• extension-authorization — required prerequisite for the per-user (§4) and admin-key (§9) variants; skipped for fully-anonymous (§10). Provides the Internet Identity login flow, the useInternetIdentity / useActor frontend plumbing, and (for §9 admin-key) the #admin role gate.
• extension-http-outcalls — sibling skill for general HTTP outcalls; you do not need it on top of openai-client, which makes its own outcalls internally.