chore: sync OpenAPI contract

[JasonLovesDoggo]

Automated sync of `contract/openapi.yaml` from the monorepo.

Source commit: trylitmus/litmus@472e2bf1b2ee3469407923dd498a51b08312638b

Review the diff, then merge. If the SDK has codegen (e.g. `pnpm generate`),
run it after merging to update generated types.

[greptile-apps]

Greptile Summary

This PR syncs the OpenAPI contract from the monorepo, adding the $sessionend event type with clear documentation distinguishing it from $abandon, and extending the Event schema with optional LLM telemetry fields (model, provider, input_tokens, output_tokens, total_tokens, duration_ms, ttft_ms, cost). All new fields are optional, making this a fully backwards-compatible change.

Confidence Score: 5/5

Safe to merge — purely additive, backwards-compatible OpenAPI contract changes with no breaking modifications.

All new fields are optional and all changes are additive. The single finding is a P2 style suggestion about potential token-count inconsistency with no immediate correctness risk.

No files require special attention.

Important Files Changed

Filename	Overview
contract/openapi.yaml	Adds $sessionend event type and optional LLM telemetry fields to the Event schema; all changes are backwards-compatible and well-documented.

Entity Relationship Diagram

%%{init: {'theme': 'neutral'}}%%
erDiagram
    Event {
        string id PK
        string session_id
        EventType type
        string project_id
        string prompt_id
        string prompt_version
        string generation_id
        string user_id
        string model
        string provider
        integer input_tokens
        integer output_tokens
        integer total_tokens
        integer duration_ms
        integer ttft_ms
        number cost
        object metadata
        string timestamp
    }

    EventType {
        string value
    }

    IngestRequest {
        array events
    }

    IngestResponse {
        integer accepted
    }

    IngestRequest ||--|{ Event : "contains"
    Event }o--|| EventType : "has"

Loading

Prompt To Fix All With AI

This is a comment left during a code review.
Path: contract/openapi.yaml
Line: 152-155

Comment:
**`total_tokens` is derivable but not constrained**

The schema accepts `input_tokens`, `output_tokens`, and `total_tokens` as independent optional integers. A client could submit values where `total_tokens != input_tokens + output_tokens` with no schema-level warning. Since this is an ingest API that stores what it receives, inconsistent token totals would silently pollute analytics. Consider adding a note in the description (or a server-side validation rule) that `total_tokens` is expected to equal `input_tokens + output_tokens` when all three are present.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "chore: sync OpenAPI contract from monore..." | Re-trigger Greptile}

[greptile-apps]

total_tokens is derivable but not constrained

The schema accepts input_tokens, output_tokens, and total_tokens as independent optional integers. A client could submit values where total_tokens != input_tokens + output_tokens with no schema-level warning. Since this is an ingest API that stores what it receives, inconsistent token totals would silently pollute analytics. Consider adding a note in the description (or a server-side validation rule) that total_tokens is expected to equal input_tokens + output_tokens when all three are present.

Prompt To Fix With AI

This is a comment left during a code review.
Path: contract/openapi.yaml
Line: 152-155

Comment:
**`total_tokens` is derivable but not constrained**

The schema accepts `input_tokens`, `output_tokens`, and `total_tokens` as independent optional integers. A client could submit values where `total_tokens != input_tokens + output_tokens` with no schema-level warning. Since this is an ingest API that stores what it receives, inconsistent token totals would silently pollute analytics. Consider adding a note in the description (or a server-side validation rule) that `total_tokens` is expected to equal `input_tokens + output_tokens` when all three are present.

How can I resolve this? If you propose a fix, please make it concise.