> ## Documentation Index
> Fetch the complete documentation index at: https://docs.getbifrost.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Test Harness Coverage

> Per-provider matrix of features exercised by Bifrost's end-to-end Postman/newman test harness.

## Overview

Bifrost ships a comprehensive end-to-end test harness (`tests/e2e/api/collections/provider-harness.json`) that exercises every provider's translation surface. This page documents which features are covered for each provider, sourced from each upstream's official docs and verified against what's in the harness collection today.

**Total: 725 requests across 12 folders** covering native API, provider-native drop-in routes (`/openai`, `/anthropic`, `/bedrock`, `/genai`), umbrella SDK drop-in shapes (`/langchain`, `/litellm`, `/pydanticai`, `/cursor`, `/cohere`), cross-model routing, passthrough endpoints, an endpoint × provider × modality matrix (chat / embeddings / audio / images), feature variations, and explicit backlog coverage.

**`[PREVIEW]` tag**: 25 requests prefixed `[PREVIEW]` are gated behind `INCLUDE_PREVIEW=1` (default-skipped) because they target account/region-scoped resources (preview-model deployments, vector stores, cached content references, MCP servers, audio-capable deployments) that the harness can't provision in arbitrary environments. Run `make run-provider-harness-test INCLUDE_PREVIEW=1` to include them.

Run it with:

```bash theme={null}
make run-provider-harness-test
```

Output:

* `tmp/newman-report.html` — rich HTML report
* `tmp/harness-failures.md` — categorized failures + coverage matrices
* Interactive viewer at `http://localhost:8090` with Resend + Copy curl

## Status legend

* `✅` — exercised by the harness, expected to pass against a properly-configured upstream
* `✅*` — exercised, but needs an environment-side resource the harness can't manufacture (vector store, cached content reference, real audio bytes, MCP server, preview deployment, etc.). These rows are typically `[PREVIEW]`-tagged in the collection so they default-skip; opt in with `make run-provider-harness-test INCLUDE_PREVIEW=1`
* `❌` — provider supports this feature but the harness doesn't yet exercise it (gap; PRs welcome)

Features a provider doesn't natively support are simply omitted from that provider's table — there's no `N/A` row, since each table only lists features within that provider's own API surface.

## Per-provider coverage

### OpenAI

| Feature                                       | Status |
| --------------------------------------------- | ------ |
| Basic chat                                    | ✅      |
| System message                                | ✅      |
| Multi-turn conversation                       | ✅      |
| Streaming (SSE)                               | ✅      |
| Stop sequences                                | ✅      |
| Sampling params (temperature / top\_p)        | ✅      |
| Logprobs / top\_logprobs                      | ✅      |
| Seed (deterministic outputs)                  | ✅      |
| Predicted outputs                             | ✅      |
| Function calling (custom tool)                | ✅      |
| Tool choice forced (`required`)               | ✅      |
| Tool choice specific function                 | ✅      |
| Parallel tool calls                           | ✅      |
| Strict tool input                             | ✅      |
| MCP toolset                                   | ✅\*    |
| Web search (basic)                            | ✅      |
| Code interpreter (Responses API)              | ✅      |
| File search (vector store)                    | ✅\*    |
| Computer use (Responses API)                  | ✅\*    |
| Vision (image input)                          | ✅      |
| PDF input                                     | ✅\*    |
| Audio input                                   | ✅\*    |
| Reasoning effort (`reasoning_effort`)         | ✅      |
| Reasoning summary (Responses API)             | ✅      |
| Structured output (`json_schema`)             | ✅      |
| Response format JSON object                   | ✅      |
| Prompt caching (ephemeral)                    | ✅      |
| Stream options w/ usage                       | ✅      |
| Service tier (`auto` / `flex` / `priority`)   | ✅      |
| Background mode (Responses async)             | ✅      |
| Truncation strategy (`auto`)                  | ✅      |
| Include array (Responses)                     | ✅      |
| Custom tool (Responses)                       | ✅      |
| Skills / container                            | ✅      |
| Token counting (`/v1/responses/input_tokens`) | ✅      |
| Batch API (create / list)                     | ✅      |
| Files API (list)                              | ✅      |
| Models list                                   | ✅      |

### Anthropic

| Feature                                                                | Status |
| ---------------------------------------------------------------------- | ------ |
| Basic chat                                                             | ✅      |
| System message                                                         | ✅      |
| Multi-turn conversation                                                | ✅      |
| Streaming (SSE)                                                        | ✅      |
| Stop sequences                                                         | ✅      |
| Function calling (custom tool)                                         | ✅      |
| Tool choice forced (`any`)                                             | ✅      |
| Tool choice specific function                                          | ✅      |
| Parallel tool calls                                                    | ✅      |
| Strict tool input                                                      | ✅      |
| Tool input examples                                                    | ✅      |
| Defer loading                                                          | ✅      |
| Allowed callers                                                        | ✅      |
| Eager input streaming                                                  | ✅      |
| Tool search (BM25 / regex)                                             | ✅      |
| MCP toolset                                                            | ✅\*    |
| Web search (basic / dynamic filtering / domain filter / user location) | ✅      |
| Web fetch                                                              | ✅      |
| Code execution                                                         | ✅      |
| Computer use                                                           | ✅      |
| Text editor tool                                                       | ✅      |
| Bash tool                                                              | ✅      |
| Memory tool                                                            | ✅      |
| Vision (image input)                                                   | ✅      |
| PDF input (URL or base64 source)                                       | ✅      |
| Citations on document blocks                                           | ✅      |
| Extended thinking (`thinking.budget_tokens`)                           | ✅      |
| Adaptive thinking (`thinking.adaptive`)                                | ✅      |
| Interleaved thinking (beta)                                            | ✅      |
| Structured output (`json_schema`)                                      | ✅      |
| Output config / effort                                                 | ✅      |
| Prompt caching (ephemeral)                                             | ✅      |
| Prompt caching (1-hour TTL)                                            | ✅      |
| Service tier                                                           | ✅      |
| `anthropic-beta` header                                                | ✅      |
| Skills / container                                                     | ✅      |
| Context management / 1M context                                        | ✅      |
| Compaction beta                                                        | ✅      |
| Token-efficient tools beta                                             | ✅      |
| Fine-grained tool streaming                                            | ✅      |
| Fast mode (Opus 4.6)                                                   | ✅\*    |
| Redact thinking beta                                                   | ✅      |
| Token counting (`/v1/messages/count_tokens`)                           | ✅      |
| Batch API (create / list)                                              | ✅      |
| Files API (list)                                                       | ✅      |
| Models list                                                            | ✅      |

### Bedrock

| Feature                                                                | Status |
| ---------------------------------------------------------------------- | ------ |
| Basic chat                                                             | ✅      |
| System message                                                         | ✅      |
| Multi-turn conversation                                                | ✅      |
| Streaming (SSE / AWS event-stream)                                     | ✅      |
| Stop sequences                                                         | ✅      |
| Sampling params (temperature OR top\_p, not both on Anthropic models)  | ✅      |
| Function calling                                                       | ✅      |
| Tool choice forced                                                     | ✅      |
| Tool choice specific function                                          | ✅      |
| Parallel tool calls                                                    | ✅      |
| MCP toolset                                                            | ✅      |
| Web search (basic / dynamic filtering / domain filter / user location) | ✅      |
| Web fetch                                                              | ✅      |
| Code execution                                                         | ✅      |
| Computer use                                                           | ✅      |
| Text editor tool                                                       | ✅      |
| Bash tool                                                              | ✅      |
| Memory tool                                                            | ✅      |
| Vision (image; URLs auto-fetched + inlined by Bifrost)                 | ✅      |
| PDF input (URLs auto-fetched + inlined)                                | ✅      |
| Citations on document blocks                                           | ✅      |
| Extended thinking (`thinking.budget_tokens`)                           | ✅      |
| Adaptive thinking (Opus 4.7 via `/v1/chat`)                            | ✅      |
| Interleaved thinking (beta)                                            | ✅      |
| Structured output (`json_schema` via tool-mode workaround)             | ✅      |
| Output config / effort                                                 | ✅      |
| Prompt caching (ephemeral)                                             | ✅      |
| Prompt caching (1-hour TTL)                                            | ✅      |
| `anthropic-beta` header passthrough                                    | ✅      |
| Context management / 1M context                                        | ✅      |
| Service tier (`auto`)                                                  | ✅      |
| Performance config (`latency: optimized`)                              | ✅      |
| Request metadata                                                       | ✅      |
| Cross-region inference (`global.` prefix)                              | ✅      |
| Cross-region inference (`us.` prefix)                                  | ✅      |
| Native Converse (`/bedrock/model/{m}/converse`)                        | ✅      |
| Native InvokeModel (`/bedrock/model/{m}/invoke`)                       | ✅      |
| Model invocation jobs (Batch API equivalent)                           | ✅      |
| Batch API                                                              | ✅      |

### Gemini (Google AI Studio)

| Feature                                                                    | Status |
| -------------------------------------------------------------------------- | ------ |
| Basic chat                                                                 | ✅      |
| System message                                                             | ✅      |
| Multi-turn conversation                                                    | ✅      |
| Streaming (SSE)                                                            | ✅      |
| Stop sequences                                                             | ✅      |
| Sampling params (temperature / top\_p / top\_k)                            | ✅      |
| Presence + frequency penalty                                               | ✅      |
| Logprobs                                                                   | ✅      |
| Function calling                                                           | ✅      |
| Tool choice forced (`any`)                                                 | ✅      |
| Tool choice specific function                                              | ✅      |
| Parallel tool calls                                                        | ✅      |
| Web search (basic)                                                         | ✅      |
| Code execution                                                             | ✅      |
| URL context tool                                                           | ✅      |
| Google search grounding                                                    | ✅      |
| Vision (image input)                                                       | ✅      |
| PDF input                                                                  | ✅\*    |
| Audio input                                                                | ✅      |
| YouTube URL input                                                          | ✅      |
| Thinking budget (`thinkingConfig`)                                         | ✅      |
| Structured output (`json_schema`)                                          | ✅      |
| Response MIME type                                                         | ✅      |
| Prompt caching (implicit, via cached content)                              | ✅      |
| Cached content reference (`cachedContent: "cachedContents/{id}"`)          | ✅\*    |
| Cached contents lifecycle (`POST/GET/PATCH/DELETE /v1beta/cachedContents`) | ❌      |
| Cached contents list (`GET /v1beta/cachedContents`)                        | ✅      |
| Safety settings                                                            | ✅      |
| Token counting (`:countTokens`)                                            | ✅      |
| Files API (list)                                                           | ✅      |
| Models list                                                                | ✅      |

### Vertex AI

| Feature                                                                             | Status |
| ----------------------------------------------------------------------------------- | ------ |
| Basic chat                                                                          | ✅      |
| System message                                                                      | ✅      |
| Multi-turn conversation                                                             | ✅      |
| Streaming (SSE)                                                                     | ✅      |
| Sampling params (temperature / top\_p)                                              | ✅      |
| Stop sequences                                                                      | ✅      |
| Function calling                                                                    | ✅      |
| Tool choice forced                                                                  | ✅      |
| Parallel function calls (Gemini)                                                    | ✅      |
| Defer loading (Anthropic)                                                           | ✅      |
| Allowed callers (Anthropic)                                                         | ✅      |
| Tool search (Anthropic BM25)                                                        | ✅      |
| MCP toolset                                                                         | ✅\*    |
| Web search (basic / dynamic filtering / domain filter / user location)              | ✅      |
| Web fetch                                                                           | ✅      |
| Code execution                                                                      | ✅      |
| Google search grounding                                                             | ✅      |
| Computer use (Anthropic)                                                            | ✅      |
| Text editor tool (Anthropic)                                                        | ✅      |
| Bash tool (Anthropic)                                                               | ✅      |
| Memory tool (Anthropic)                                                             | ✅      |
| Vision (image input)                                                                | ✅      |
| PDF input (URLs auto-fetched + inlined for Vertex-Anthropic)                        | ✅      |
| Audio input (Gemini)                                                                | ✅\*    |
| Citations on document blocks                                                        | ✅      |
| Extended thinking (`thinking.budget_tokens`)                                        | ✅      |
| Adaptive thinking                                                                   | ✅      |
| Thinking budget (Gemini `thinkingConfig`)                                           | ✅      |
| Interleaved thinking (Anthropic beta)                                               | ✅      |
| Structured output (`json_schema`)                                                   | ✅      |
| Response MIME type (Gemini)                                                         | ✅      |
| Output config / effort (Anthropic)                                                  | ✅      |
| Prompt caching (ephemeral)                                                          | ✅      |
| Prompt caching (1-hour TTL)                                                         | ✅      |
| Cached contents lifecycle (`POST/GET/PATCH/DELETE /v1/projects/.../cachedContents`) | ❌      |
| `anthropic-beta` header passthrough                                                 | ✅      |
| Safety settings (Gemini)                                                            | ✅      |
| Context management / 1M context (Anthropic)                                         | ✅      |
| Token counting                                                                      | ✅      |
| Model Garden (Llama / Mistral)                                                      | ✅\*    |

### Azure OpenAI

| Feature                                     | Status |
| ------------------------------------------- | ------ |
| Basic chat                                  | ✅      |
| System message                              | ✅      |
| Multi-turn conversation                     | ✅      |
| Streaming (SSE)                             | ✅      |
| Stop sequences                              | ✅      |
| Sampling params (temperature / top\_p)      | ✅      |
| Logprobs / top\_logprobs                    | ❌      |
| Seed (deterministic outputs)                | ❌      |
| Predicted outputs                           | ❌      |
| Function calling                            | ✅      |
| Tool choice forced                          | ✅      |
| Tool choice specific function               | ❌      |
| Parallel tool calls                         | ✅      |
| Strict tool input                           | ❌      |
| Code interpreter (Responses preview)        | ✅      |
| File search (Responses preview)             | ✅\*    |
| Vision (image input)                        | ✅      |
| Audio input (`gpt-4o-audio-preview`)        | ✅\*    |
| Reasoning effort (`o3` deployment)          | ✅\*    |
| Structured output (`json_schema`)           | ✅      |
| Response format JSON object                 | ❌      |
| Service tier (`auto` / `flex` / `priority`) | ✅      |
| Skills / container                          | ✅      |
| Azure On Your Data (`azure_search`)         | ✅      |

**Bifrost-side normalizations applied automatically** (don't appear as separate rows):

* Vision URL images on Bedrock — fetched and inlined as base64 (Bedrock Converse only accepts inline bytes)
* PDF URL documents on Bedrock — same fetch+inline path
* PDF URL documents on Vertex Claude — same (Vertex-Anthropic doesn't accept URL document sources)
* Anthropic-style `{type:"document",source:{...}}` blocks on `/v1/chat/completions` — normalized to `{type:"file",file:{...}}` at JSON unmarshal so every provider's converter sees the same shape

## Modalities (`8. Criss-Cross`)

The harness exercises every non-chat modality across providers via both native `/v1/<modality>` routes and OpenAI / GenAI drop-in shapes. Cells marked `N/A` are not applicable (provider does not expose the modality through Bifrost, or the cell is the provider talking to itself through its own drop-in shape). Cells the harness deliberately skips at run time (encoded as `[SKIP]` in the collection) inherit `N/A` here.

| Modality (route)                                                       | OpenAI                       | Anthropic | Bedrock                        | Gemini                     | Vertex                   | Azure             |
| ---------------------------------------------------------------------- | ---------------------------- | --------- | ------------------------------ | -------------------------- | ------------------------ | ----------------- |
| Embeddings, native (`/v1/embeddings`)                                  | ✅ (`text-embedding-3-small`) | N/A       | ✅ (`titan-embed-text-v2`)      | ✅ (`gemini-embedding-001`) | ✅ (`text-embedding-005`) | ✅                 |
| Embeddings via OpenAI drop-in (`/openai/v1/embeddings`)                | N/A                          | N/A       | ✅                              | ✅                          | ✅                        | ✅                 |
| Embeddings via GenAI drop-in (`/genai/v1beta/models/{m}:embedContent`) | ✅                            | N/A       | ✅                              | N/A                        | ✅                        | ✅                 |
| Audio transcription, native (`/v1/audio/transcriptions`)               | ✅ (`whisper-1`)              | N/A       | N/A                            | ✅ (`gemini-2.5-flash`)     | N/A                      | ✅                 |
| Audio transcription via OpenAI drop-in                                 | N/A                          | N/A       | N/A                            | ✅                          | N/A                      | ✅                 |
| Text-to-speech, native (`/v1/audio/speech`)                            | ✅ (`tts-1`)                  | N/A       | N/A                            | N/A                        | N/A                      | ✅                 |
| Text-to-speech via OpenAI drop-in                                      | N/A                          | N/A       | N/A                            | N/A                        | N/A                      | ✅                 |
| Image generation, native (`/v1/images/generations`)                    | ✅ (`gpt-image-1`)            | N/A       | ✅ (`titan-image-generator-v2`) | ✅ (`imagen-4.0`)           | ✅ (`imagen-4.0`)         | ✅ (`gpt-image-2`) |
| Image generation via OpenAI drop-in                                    | N/A                          | N/A       | ✅                              | ✅                          | ✅                        | ✅                 |

Folder 8 also contains a `8.6 Feature combinations` sub-folder (26 requests) that exercises tool-calling, vision, JSON/structured-output, and reasoning across the `/v1/chat/completions` × `/openai` × `/anthropic` × `/bedrock` × `/genai` shape grid - these are tabulated in the cross-cutting matrices below.

## Cross-cutting (Bifrost-specific)

These exercise Bifrost's translation layer between provider shapes — every check uses the unified `POST /v1/chat/completions` endpoint with `provider/model` prefix routing.

### Translation-layer matrices (`/v1/chat/completions` with `provider/model` prefix)

Each row is a dedicated `Round N` sub-folder under `12. Backlog Coverage`. The number in parentheses is the count of (provider, model) cells exercised today.

| Matrix                                        | Status |
| --------------------------------------------- | ------ |
| Cross-model routing (50 models × 5 providers) | ✅      |
| System message matrix (11)                    | ✅      |
| Multi-turn matrix (11)                        | ✅      |
| Streaming matrix (18)                         | ✅      |
| Stop sequences matrix (11)                    | ✅      |
| Function calling matrix (19)                  | ✅      |
| Tool choice forced matrix (13)                | ✅      |
| Vision matrix (15)                            | ✅      |
| PDF input matrix (4)                          | ✅      |
| Structured output / json\_schema matrix (14)  | ✅      |
| Extended / adaptive thinking matrix (6)       | ✅      |
| Prompt caching matrix (6)                     | ✅      |
| Web search matrix (6)                         | ✅      |
| Code execution matrix (3)                     | ✅      |

### Drop-in (native-shape) matrices

These exercise the same features but against the *provider-native drop-in* routes (`/openai`, `/anthropic`, `/bedrock`, `/genai`) rather than `/v1/chat/completions`.

| Matrix                        | Status |
| ----------------------------- | ------ |
| Drop-in streaming (9)         | ✅      |
| Drop-in function calling (9)  | ✅      |
| Drop-in vision (8)            | ✅      |
| Drop-in structured output (8) | ✅      |

### Umbrella-SDK drop-in shapes

Bifrost exposes umbrella SDK routes that accept the OpenAI / Anthropic / Gemini / Bedrock / Cohere request shape byte-for-byte and dispatch to the right typed provider underneath. Each umbrella has its own smoke folder plus a shared vision matrix.

| Umbrella route                                                                                                       | Coverage                                                      |
| -------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------- |
| `/cohere`                                                                                                            | Basic chat, streaming, multi-turn, tools, list models (5)     |
| `/langchain`                                                                                                         | OpenAI / Anthropic / Gemini / Bedrock / Cohere shape chat (5) |
| `/litellm`                                                                                                           | OpenAI / Anthropic / Gemini / Bedrock / Cohere shape chat (5) |
| `/pydanticai`                                                                                                        | OpenAI / Anthropic / Gemini / Bedrock / Cohere shape chat (5) |
| `/cursor`                                                                                                            | OpenAI / Anthropic / Gemini / Bedrock shape chat (4)          |
| Drop-in umbrella vision matrix (`/langchain`, `/litellm`, `/pydanticai`, `/cursor` × OpenAI/Anthropic/Gemini shapes) | ✅ (12)                                                        |

### Bifrost-only behaviors

| Feature                                                | Status |
| ------------------------------------------------------ | ------ |
| Failover via `X-Bifrost-Fallback-Models`               | ✅      |
| Virtual key auth via `X-Bifrost-VK`                    | ✅      |
| Sampling-params auto-strip for Opus 4.7+               | ✅      |
| Computer-use generation auto-correct (4.5↔4.6 pairing) | ✅      |
| Rate limit propagation with `Retry-After`              | ❌      |

## Passthrough surface (`*_passthrough/*`)

Catch-all forwarding routes that strip incoming auth headers and inject Bifrost's configured provider key.

| Feature                           | OpenAI | Anthropic | Bedrock | Azure | Gemini |
| --------------------------------- | ------ | --------- | ------- | ----- | ------ |
| Basic chat                        | ✅      | ✅         | N/A     | ✅     | ✅      |
| Streaming                         | ✅      | ✅         | N/A     | ✅     | ✅      |
| Multi-turn                        | N/A    | ✅         | N/A     | N/A   | N/A    |
| Vision                            | ✅      | ✅         | N/A     | ✅     | ✅      |
| Function calling / tool use       | N/A    | ✅         | N/A     | ✅     | ✅      |
| Structured output (`json_schema`) | ✅      | N/A       | N/A     | ✅     | N/A    |
| Web search                        | ✅      | ✅         | N/A     | N/A   | ✅      |
| Code execution / code interpreter | ✅      | N/A       | N/A     | N/A   | ✅      |
| Computer use                      | N/A    | ✅         | N/A     | N/A   | N/A    |
| Extended thinking                 | N/A    | ✅         | N/A     | N/A   | N/A    |
| Prompt caching                    | N/A    | ✅         | N/A     | N/A   | N/A    |

Covered across the `Passthrough Backlog` folder + `Cross-Cut Round 28: Passthrough Advanced Matrix` (24 requests total).

**Bedrock**: passthrough is **not supported by design**. AWS SigV4 signing requires bifrost to sign the request with its own credentials, which fundamentally conflicts with byte-for-byte forwarding. Use the typed `/bedrock/model/{modelId}/converse`, `/converse-stream`, or `/invoke` routes instead — those go through bifrost's typed Bedrock provider with proper sigv4 handling.

**Vertex**: no passthrough variant. Google OAuth bearer tokens are rotated per-request and can't be bridged through a byte-for-byte forward.

## Coverage by transport route

| Route                  | What it tests                                                                                                                                  |
| ---------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- |
| **drop-in (native)**   | Provider-native shape via `/openai`, `/anthropic`, `/bedrock`, `/genai`. Most thorough coverage.                                               |
| **drop-in (umbrella)** | SDK-umbrella shapes via `/langchain`, `/litellm`, `/pydanticai`, `/cursor`, `/cohere`. Smoke + vision matrix.                                  |
| **cross-model**        | Unified `/v1/chat/completions` with `provider/model` prefix. Tests Bifrost's translation layer.                                                |
| **modality**           | `8.3` – `8.5` exercise `/v1/embeddings`, `/v1/audio/transcriptions`, `/v1/audio/speech`, `/v1/images/generations` across providers + drop-ins. |
| **passthrough**        | `/*_passthrough/*` byte-for-byte forwarding with auth-header strip + Bifrost key injection.                                                    |

## Known gaps that need external setup

These cells stay `❌` even after running because they require provider-side state the harness can't manufacture:

* **OpenAI File Search** — needs a real `vs_*` vector store (`[PREVIEW]`-tagged)
* **OpenAI / Azure Audio Input** — needs real base64 audio bytes (`[PREVIEW]`-tagged)
* **OpenAI / Anthropic Batch creation** — needs a real input file ID
* **Gemini Cached Content reference** — the lifecycle endpoints (create/list/retrieve/update/delete) work end-to-end; only the *referencing* tests (passing `cachedContents/{id}` to `generateContent`) need a pre-provisioned cache with 32k+ tokens of content (Gemini's minimum) (`[PREVIEW]`-tagged)
* **Vertex Anthropic features in `us-central1`** — region-restricted unless `GOOGLE_LOCATION=global`
* **Vertex preview-model deployments** (Gemini-3.x, etc.) — `[PREVIEW]`-tagged; require account access
* **Vertex-Anthropic URL document sources** — Vertex doesn't accept URL document sources upstream; bifrost auto-fetches and inlines via `inlineDocumentURLs` for parity with direct Anthropic
* **Azure preview deployments** (`o3` / `gpt-4o-audio-preview` / `computer-use-preview`) — `[PREVIEW]`-tagged; require deployment provisioning
* **MCP toolset tests** — `[PREVIEW]`-tagged; need a reachable MCP server

## Coverage report layout

When you run the harness, `tmp/harness-failures.md` is generated with three matrices:

1. **Feature × Provider** — every feature row × every provider column
2. **Feature × Route** — same features × `drop-in` / `cross-model` / `passthrough`
3. **Per-(provider, model)** — every distinct provider/model tuple, with the exact features each one exercised

Plus three "missing coverage" lists (per-provider, per-route, per-model) that surface gaps as a backlog.

## Extending coverage

The full backlog of candidate test additions lives in [`tests/e2e/api/HARNESS_COVERAGE_BACKLOG.md`](https://github.com/maximhq/bifrost/blob/main/tests/e2e/api/HARNESS_COVERAGE_BACKLOG.md) — provider-by-provider feature inventory sourced from each provider's official docs. Adding a new test is a one-line entry in the relevant sub-folder of `provider-harness.json`.