|
| 1 | +--- |
| 2 | +name: add-hosted-key |
| 3 | +description: Add hosted API key support to a tool so Sim provides the key when users don't bring their own. Use when adding hosted keys, BYOK support, hideWhenHosted, or hosted key pricing to a tool or block. |
| 4 | +--- |
| 5 | + |
| 6 | +# Adding Hosted Key Support to a Tool |
| 7 | + |
| 8 | +When a tool has hosted key support, Sim provides its own API key if the user hasn't configured one (via BYOK or env var). Usage is metered and billed to the workspace. |
| 9 | + |
| 10 | +## Overview |
| 11 | + |
| 12 | +| Step | What | Where | |
| 13 | +|------|------|-------| |
| 14 | +| 1 | Register BYOK provider ID | `tools/types.ts`, `app/api/workspaces/[id]/byok-keys/route.ts` | |
| 15 | +| 2 | Research the API's pricing and rate limits | API docs / pricing page (before writing any code) | |
| 16 | +| 3 | Add `hosting` config to the tool | `tools/{service}/{action}.ts` | |
| 17 | +| 4 | Hide API key field when hosted | `blocks/blocks/{service}.ts` | |
| 18 | +| 5 | Add to BYOK settings UI | BYOK settings component (`byok.tsx`) | |
| 19 | +| 6 | Summarize pricing and throttling comparison | Output to user (after all code changes) | |
| 20 | + |
| 21 | +## Step 1: Register the BYOK Provider ID |
| 22 | + |
| 23 | +Add the new provider to the `BYOKProviderId` union in `tools/types.ts`: |
| 24 | + |
| 25 | +```typescript |
| 26 | +export type BYOKProviderId = |
| 27 | + | 'openai' |
| 28 | + | 'anthropic' |
| 29 | + // ...existing providers |
| 30 | + | 'your_service' |
| 31 | +``` |
| 32 | +
|
| 33 | +Then add it to `VALID_PROVIDERS` in `app/api/workspaces/[id]/byok-keys/route.ts`: |
| 34 | +
|
| 35 | +```typescript |
| 36 | +const VALID_PROVIDERS = ['openai', 'anthropic', 'google', 'mistral', 'your_service'] as const |
| 37 | +``` |
| 38 | + |
| 39 | +## Step 2: Research the API's Pricing Model and Rate Limits |
| 40 | + |
| 41 | +**Before writing any `getCost` or `rateLimit` code**, look up the service's official documentation for both pricing and rate limits. You need to understand: |
| 42 | + |
| 43 | +### Pricing |
| 44 | + |
| 45 | +1. **How the API charges** — per request, per credit, per token, per step, per minute, etc. |
| 46 | +2. **Whether the API reports cost in its response** — look for fields like `creditsUsed`, `costDollars`, `tokensUsed`, or similar in the response body or headers |
| 47 | +3. **Whether cost varies by endpoint/options** — some APIs charge more for certain features (e.g., Firecrawl charges 1 credit/page base but +4 for JSON format, +4 for enhanced mode) |
| 48 | +4. **The dollar-per-unit rate** — what each credit/token/unit costs in dollars on our plan |
| 49 | + |
| 50 | +### Rate Limits |
| 51 | + |
| 52 | +1. **What rate limits the API enforces** — requests per minute/second, tokens per minute, concurrent requests, etc. |
| 53 | +2. **Whether limits vary by plan tier** — free vs paid vs enterprise often have different ceilings |
| 54 | +3. **Whether limits are per-key or per-account** — determines whether adding more hosted keys actually increases total throughput |
| 55 | +4. **What the API returns when rate limited** — HTTP 429, `Retry-After` header, error body format, etc. |
| 56 | +5. **Whether there are multiple dimensions** — some APIs limit both requests/min AND tokens/min independently |
| 57 | + |
| 58 | +Search the API's docs/pricing page (use WebSearch/WebFetch). Capture the pricing model as a comment in `getCost` so future maintainers know the source of truth. |
| 59 | + |
| 60 | +### Setting Our Rate Limits |
| 61 | + |
| 62 | +Our rate limiter (`lib/core/rate-limiter/hosted-key/`) uses a token-bucket algorithm applied **per billing actor** (workspace). It supports two modes: |
| 63 | + |
| 64 | +- **`per_request`** — simple; just `requestsPerMinute`. Good when the API charges flat per-request or cost doesn't vary much. |
| 65 | +- **`custom`** — `requestsPerMinute` plus additional `dimensions` (e.g., `tokens`, `search_units`). Each dimension has its own `limitPerMinute` and an `extractUsage` function that reads actual usage from the response. Use when the API charges on a variable metric (tokens, credits) and you want to cap that metric too. |
| 66 | + |
| 67 | +When choosing values for `requestsPerMinute` and any dimension limits: |
| 68 | + |
| 69 | +- **Stay well below the API's per-key limit** — our keys are shared across all workspaces. If the API allows 60 RPM per key and we have 3 keys, the global ceiling is ~180 RPM. Set the per-workspace limit low enough (e.g., 20-60 RPM) that many workspaces can coexist without collectively hitting the API's ceiling. |
| 70 | +- **Account for key pooling** — our round-robin distributes requests across `N` hosted keys, so the effective API-side rate per key is `(total requests) / N`. But per-workspace limits are enforced *before* key selection, so they apply regardless of key count. |
| 71 | +- **Prefer conservative defaults** — it's easy to raise limits later but hard to claw back after users depend on high throughput. |
| 72 | + |
| 73 | +## Step 3: Add `hosting` Config to the Tool |
| 74 | + |
| 75 | +Add a `hosting` object to the tool's `ToolConfig`. This tells the execution layer how to acquire hosted keys, calculate cost, and rate-limit. |
| 76 | + |
| 77 | +```typescript |
| 78 | +hosting: { |
| 79 | + envKeyPrefix: 'YOUR_SERVICE_API_KEY', |
| 80 | + apiKeyParam: 'apiKey', |
| 81 | + byokProviderId: 'your_service', |
| 82 | + pricing: { |
| 83 | + type: 'custom', |
| 84 | + getCost: (_params, output) => { |
| 85 | + if (output.creditsUsed == null) { |
| 86 | + throw new Error('Response missing creditsUsed field') |
| 87 | + } |
| 88 | + const creditsUsed = output.creditsUsed as number |
| 89 | + const cost = creditsUsed * 0.001 // dollars per credit |
| 90 | + return { cost, metadata: { creditsUsed } } |
| 91 | + }, |
| 92 | + }, |
| 93 | + rateLimit: { |
| 94 | + mode: 'per_request', |
| 95 | + requestsPerMinute: 100, |
| 96 | + }, |
| 97 | +}, |
| 98 | +``` |
| 99 | + |
| 100 | +### Hosted Key Env Var Convention |
| 101 | + |
| 102 | +Keys use a numbered naming pattern driven by a count env var: |
| 103 | + |
| 104 | +``` |
| 105 | +YOUR_SERVICE_API_KEY_COUNT=3 |
| 106 | +YOUR_SERVICE_API_KEY_1=sk-... |
| 107 | +YOUR_SERVICE_API_KEY_2=sk-... |
| 108 | +YOUR_SERVICE_API_KEY_3=sk-... |
| 109 | +``` |
| 110 | + |
| 111 | +The `envKeyPrefix` value (`YOUR_SERVICE_API_KEY`) determines which env vars are read at runtime. Adding more keys only requires bumping the count and adding the new env var. |
| 112 | + |
| 113 | +### Pricing: Prefer API-Reported Cost |
| 114 | + |
| 115 | +Always prefer using cost data returned by the API (e.g., `creditsUsed`, `costDollars`). This is the most accurate because it accounts for variable pricing tiers, feature modifiers, and plan-level discounts. |
| 116 | + |
| 117 | +**When the API reports cost** — use it directly and throw if missing: |
| 118 | + |
| 119 | +```typescript |
| 120 | +pricing: { |
| 121 | + type: 'custom', |
| 122 | + getCost: (params, output) => { |
| 123 | + if (output.creditsUsed == null) { |
| 124 | + throw new Error('Response missing creditsUsed field') |
| 125 | + } |
| 126 | + // $0.001 per credit — from https://example.com/pricing |
| 127 | + const cost = (output.creditsUsed as number) * 0.001 |
| 128 | + return { cost, metadata: { creditsUsed: output.creditsUsed } } |
| 129 | + }, |
| 130 | +}, |
| 131 | +``` |
| 132 | + |
| 133 | +**When the API does NOT report cost** — compute it from params/output based on the pricing docs, but still validate the data you depend on: |
| 134 | + |
| 135 | +```typescript |
| 136 | +pricing: { |
| 137 | + type: 'custom', |
| 138 | + getCost: (params, output) => { |
| 139 | + if (!Array.isArray(output.searchResults)) { |
| 140 | + throw new Error('Response missing searchResults, cannot determine cost') |
| 141 | + } |
| 142 | + // Serper: 1 credit for <=10 results, 2 credits for >10 — from https://serper.dev/pricing |
| 143 | + const credits = Number(params.num) > 10 ? 2 : 1 |
| 144 | + return { cost: credits * 0.001, metadata: { credits } } |
| 145 | + }, |
| 146 | +}, |
| 147 | +``` |
| 148 | + |
| 149 | +**`getCost` must always throw** if it cannot determine cost. Never silently fall back to a default — this would hide billing inaccuracies. |
| 150 | + |
| 151 | +### Capturing Cost Data from the API |
| 152 | + |
| 153 | +If the API returns cost info, capture it in `transformResponse` so `getCost` can read it from the output: |
| 154 | + |
| 155 | +```typescript |
| 156 | +transformResponse: async (response: Response) => { |
| 157 | + const data = await response.json() |
| 158 | + return { |
| 159 | + success: true, |
| 160 | + output: { |
| 161 | + results: data.results, |
| 162 | + creditsUsed: data.creditsUsed, // pass through for getCost |
| 163 | + }, |
| 164 | + } |
| 165 | +}, |
| 166 | +``` |
| 167 | + |
| 168 | +For async/polling tools, capture it in `postProcess` when the job completes: |
| 169 | + |
| 170 | +```typescript |
| 171 | +if (jobData.status === 'completed') { |
| 172 | + result.output = { |
| 173 | + data: jobData.data, |
| 174 | + creditsUsed: jobData.creditsUsed, |
| 175 | + } |
| 176 | +} |
| 177 | +``` |
| 178 | + |
| 179 | +## Step 4: Hide the API Key Field When Hosted |
| 180 | + |
| 181 | +In the block config (`blocks/blocks/{service}.ts`), add `hideWhenHosted: true` to the API key subblock. This hides the field on hosted Sim since the platform provides the key: |
| 182 | + |
| 183 | +```typescript |
| 184 | +{ |
| 185 | + id: 'apiKey', |
| 186 | + title: 'API Key', |
| 187 | + type: 'short-input', |
| 188 | + placeholder: 'Enter your API key', |
| 189 | + password: true, |
| 190 | + required: true, |
| 191 | + hideWhenHosted: true, |
| 192 | +}, |
| 193 | +``` |
| 194 | + |
| 195 | +The visibility is controlled by `isSubBlockHiddenByHostedKey()` in `lib/workflows/subblocks/visibility.ts`, which checks the `isHosted` feature flag. |
| 196 | + |
| 197 | +## Step 5: Add to the BYOK Settings UI |
| 198 | + |
| 199 | +Add an entry to the `PROVIDERS` array in the BYOK settings component so users can bring their own key. You need the service icon from `components/icons.tsx`: |
| 200 | + |
| 201 | +```typescript |
| 202 | +{ |
| 203 | + id: 'your_service', |
| 204 | + name: 'Your Service', |
| 205 | + icon: YourServiceIcon, |
| 206 | + description: 'What this service does', |
| 207 | + placeholder: 'Enter your API key', |
| 208 | +}, |
| 209 | +``` |
| 210 | + |
| 211 | +## Step 6: Summarize Pricing and Throttling Comparison |
| 212 | + |
| 213 | +After all code changes are complete, output a detailed summary to the user covering: |
| 214 | + |
| 215 | +### What to include |
| 216 | + |
| 217 | +1. **API's pricing model** — how the service charges (per token, per credit, per request, etc.), the specific rates found in docs, and whether the API reports cost in responses. |
| 218 | +2. **Our `getCost` approach** — how we calculate cost, what fields we depend on, and any assumptions or estimates (especially when the API doesn't report exact dollar cost). |
| 219 | +3. **API's rate limits** — the documented limits (RPM, TPM, concurrent, etc.), which plan tier they apply to, and whether they're per-key or per-account. |
| 220 | +4. **Our `rateLimit` config** — what we set for `requestsPerMinute` (and dimensions if custom mode), why we chose those values, and how they compare to the API's limits. |
| 221 | +5. **Key pooling impact** — how many hosted keys we expect, and how round-robin distribution affects the effective per-key rate at the API. |
| 222 | +6. **Gaps or risks** — anything the API charges for that we don't meter, rate limit dimensions we chose not to enforce, or pricing that may be inaccurate due to variable model/tier costs. |
| 223 | + |
| 224 | +### Format |
| 225 | + |
| 226 | +Present this as a structured summary with clear headings. Example: |
| 227 | + |
| 228 | +``` |
| 229 | +### Pricing |
| 230 | +- **API charges**: $X per 1M tokens (input), $Y per 1M tokens (output) — varies by model |
| 231 | +- **Response reports cost?**: No — only token counts in `usage` field |
| 232 | +- **Our getCost**: Estimates cost at $Z per 1M total tokens based on median model pricing |
| 233 | +- **Risk**: Actual cost varies by model; our estimate may over/undercharge for cheap/expensive models |
| 234 | +
|
| 235 | +### Throttling |
| 236 | +- **API limits**: 300 RPM per key (paid tier), 60 RPM (free tier) |
| 237 | +- **Per-key or per-account**: Per key — more keys = more throughput |
| 238 | +- **Our config**: 60 RPM per workspace (per_request mode) |
| 239 | +- **With N keys**: Effective per-key rate is (total RPM across workspaces) / N |
| 240 | +- **Headroom**: Comfortable — even 10 active workspaces at full rate = 600 RPM / 3 keys = 200 RPM per key, under the 300 RPM API limit |
| 241 | +``` |
| 242 | + |
| 243 | +This summary helps reviewers verify that the pricing and rate limiting are well-calibrated and surfaces any risks that need monitoring. |
| 244 | + |
| 245 | +## Checklist |
| 246 | + |
| 247 | +- [ ] Provider added to `BYOKProviderId` in `tools/types.ts` |
| 248 | +- [ ] Provider added to `VALID_PROVIDERS` in the BYOK keys API route |
| 249 | +- [ ] API pricing docs researched — understand per-unit cost and whether the API reports cost in responses |
| 250 | +- [ ] API rate limits researched — understand RPM/TPM limits, per-key vs per-account, and plan tiers |
| 251 | +- [ ] `hosting` config added to the tool with `envKeyPrefix`, `apiKeyParam`, `byokProviderId`, `pricing`, and `rateLimit` |
| 252 | +- [ ] `getCost` throws if required cost data is missing from the response |
| 253 | +- [ ] Cost data captured in `transformResponse` or `postProcess` if API provides it |
| 254 | +- [ ] `hideWhenHosted: true` added to the API key subblock in the block config |
| 255 | +- [ ] Provider entry added to the BYOK settings UI with icon and description |
| 256 | +- [ ] Env vars documented: `{PREFIX}_COUNT` and `{PREFIX}_1..N` |
| 257 | +- [ ] Pricing and throttling summary provided to reviewer |
0 commit comments