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| 1 | +--- |
| 2 | +title: RESPAN Span-01 Backend |
| 3 | +description: Score conversation behaviors with RESPAN while preserving not-observable probability. |
| 4 | +--- |
| 5 | + |
| 6 | +<!-- markdownlint-disable MD013 --> |
| 7 | + |
| 8 | +The `respan` driver connects Polyglot Decision to RESPAN's hosted |
| 9 | +[`POST /api/v1/scores`](https://www.respan.ai/docs/apis/respan-models/score-span-behaviors) |
| 10 | +endpoint. Span-01 evaluates plain-language behavior definitions against one |
| 11 | +conversation span and returns present, absent, and not-observable probabilities. |
| 12 | + |
| 13 | +## Configure the driver |
| 14 | + |
| 15 | +Set the RESPAN API key: |
| 16 | + |
| 17 | +```dotenv |
| 18 | +RESPAN_API_KEY=your-key |
| 19 | +``` |
| 20 | + |
| 21 | +Then select the bundled preset: |
| 22 | + |
| 23 | +```php |
| 24 | +use Cognesy\Polyglot\Decision\Decision; |
| 25 | + |
| 26 | +$decision = Decision::using('respan'); |
| 27 | +``` |
| 28 | + |
| 29 | +The preset targets `https://api.respan.ai/api/v1/scores` with |
| 30 | +`span-01-free`. Override the model with `span-01-pro` when the organization has |
| 31 | +Span-01 access and sufficient credits. |
| 32 | + |
| 33 | +## Conversation input |
| 34 | + |
| 35 | +RESPAN requires an explicit conversation boundary. Pass a JSON object whose |
| 36 | +`input` list contains preceding messages and whose `output` object contains the |
| 37 | +single turn being judged: |
| 38 | + |
| 39 | +```php |
| 40 | +use Cognesy\Polyglot\Decision\Collections\Questions; |
| 41 | +use Cognesy\Polyglot\Decision\Data\JsonContent; |
| 42 | +use Cognesy\Polyglot\Decision\Questions\Noul; |
| 43 | + |
| 44 | +$answers = $decision |
| 45 | + ->withInput(JsonContent::object([ |
| 46 | + 'input' => [ |
| 47 | + ['role' => 'user', 'content' => 'My order is late again.'], |
| 48 | + ], |
| 49 | + 'output' => [ |
| 50 | + 'role' => 'assistant', |
| 51 | + 'content' => 'I am sorry. I will check the shipment now.', |
| 52 | + ], |
| 53 | + ])) |
| 54 | + ->withQuestions(Questions::of( |
| 55 | + new Noul('apology', 'The assistant apologizes for a problem.'), |
| 56 | + )) |
| 57 | + ->get(); |
| 58 | + |
| 59 | +$answer = $answers->noul('apology'); |
| 60 | +$present = $answer->probabilities()->positive(); |
| 61 | +$absent = $answer->probabilities()->negative(); |
| 62 | +$unknown = $answer->probabilities()->unknown(); |
| 63 | +``` |
| 64 | + |
| 65 | +The adapter does not guess conversation turns from a string or unstructured |
| 66 | +list. Each message must have text `content`; `role` is optional but must be a |
| 67 | +non-empty string when present. |
| 68 | + |
| 69 | +## Primitive and answer semantics |
| 70 | + |
| 71 | +| Decision primitive | Span-01 representation | Capability | |
| 72 | +| --- | --- | --- | |
| 73 | +| Noul | One independent behavior definition | Native | |
| 74 | +| Choice | Not supported by this endpoint | Unsupported | |
| 75 | +| Score | Not supported by this endpoint | Unsupported | |
| 76 | + |
| 77 | +Noul instructions become the behavior definition. Optional true and false |
| 78 | +criteria are rendered as explicit `Present when` and `Absent when` guidance. |
| 79 | +RESPAN evaluates all behaviors independently against the same span. |
| 80 | + |
| 81 | +`NoulAnswer::probability()` remains the positive/present probability. The full |
| 82 | +`NoulProbabilities` value exposes positive, negative, and unknown values. |
| 83 | +`confidence()` is the greater of positive and negative; it never treats |
| 84 | +not-observable probability as evidence for absence. |
| 85 | + |
| 86 | +## Usage, identity, and failures |
| 87 | + |
| 88 | +- `usage.input_tokens` becomes `DecisionUsage::inputTokens()`. |
| 89 | +- Output tokens remain unknown because Span-01 does not generate output. |
| 90 | +- `X-Respan-Log-Id` becomes `DecisionResponse::providerRequestId()`. |
| 91 | +- HTTP 429 and transient dependency/service failures use the normal Decision |
| 92 | + retry policy and preserve `Retry-After`. |
| 93 | +- Missing credentials, unavailable organization entitlement, and insufficient |
| 94 | + pro credits are non-retryable and reported separately from invalid payloads. |
| 95 | + |
| 96 | +The bundled model records advertise zero pricing for `span-01-free` and |
| 97 | +`$0.02` per million input tokens for `span-01-pro`. No token ceiling is recorded |
| 98 | +because RESPAN does not publish a numeric limit. |
| 99 | + |
| 100 | +The initial driver deliberately does not send `respan_params`. Polyglot does not |
| 101 | +implicitly export telemetry identities or metadata as provider logging data. |
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