Rust API Reference

Rust API Reference v1.16.0

Functions

create_client()

Create a new LLM client with simple scalar configuration.

This is the primary binding entry-point. All parameters except api_key are optional — omitting them uses the same defaults as ClientConfigBuilder.

Errors:

Returns LiterLlmError if the underlying HTTP client cannot be constructed, or if the resolved provider configuration is invalid.

Signature:

pub fn create_client(api_key: &str, base_url: Option<String>, timeout_secs: Option<u64>, max_retries: Option<u32>, model_hint: Option<String>) -> Result<DefaultClient, LiterLlmError>

Example:

let result = create_client("value", "value", 42, 42, "value")?;

Parameters:

Name	Type	Required	Description
api_key	String	Yes	The api key
base_url	Option<String>	No	The base url
timeout_secs	Option<u64>	No	The timeout secs
max_retries	Option<u32>	No	The max retries
model_hint	Option<String>	No	The model hint

Returns: DefaultClient

Errors: Returns Err(LiterLlmError).

---

create_client_from_json()

Create a new LLM client from a JSON string.

The JSON object accepts the same fields as liter-llm.toml (snake_case).

Errors:

Returns LiterLlmError::BadRequest if json is not valid JSON or contains unknown fields.

Signature:

pub fn create_client_from_json(json: &str) -> Result<DefaultClient, LiterLlmError>

Example:

let result = create_client_from_json("value")?;

Parameters:

Name	Type	Required	Description
json	String	Yes	The json

Returns: DefaultClient

Errors: Returns Err(LiterLlmError).

---

encode_data_url()

Encode bytes as a base64 data URL: data:<mime>;base64,<b64>.

mime defaults to IMAGE_PNG when None.

Signature:

pub fn encode_data_url(bytes: &[u8], mime: Option<String>) -> String

Example:

use liter_llm::image::{encode_data_url, IMAGE_PNG, IMAGE_JPEG};

let url = encode_data_url(b"\x89PNG", Some(IMAGE_PNG));
assert!(url.starts_with("data:image/png;base64,"));

let url_default = encode_data_url(b"\x89PNG", None);
assert!(url_default.starts_with("data:image/png;base64,"));

let jpeg_url = encode_data_url(b"\xff\xd8\xff", Some(IMAGE_JPEG));
assert!(jpeg_url.starts_with("data:image/jpeg;base64,"));

Parameters:

Name	Type	Required	Description
bytes	Vec<u8>	Yes	The bytes
mime	Option<String>	No	The mime

Returns: String

---

decode_data_url()

Decode a base64 data URL into DecodedDataUrl.

Returns None for:

• Non-data URLs (strings that do not start with "data:").
• Malformed prefixes (missing ";base64," marker).
• Invalid base64 payloads.

The returned MIME string is extracted verbatim from the URL prefix — it is not validated or normalised.

Signature:

pub fn decode_data_url(url: &str) -> Option<DecodedDataUrl>

Example:

use liter_llm::image::{encode_data_url, decode_data_url, IMAGE_PNG};

let url = encode_data_url(b"hello", Some(IMAGE_PNG));
let decoded = decode_data_url(&url).expect("valid data URL");
assert_eq!(decoded.mime, IMAGE_PNG);
assert_eq!(decoded.data, b"hello");

// Non-data URLs return None.
assert!(decode_data_url("<https://example.com/img.png">).is_none());

// Missing ;base64, marker returns None.
assert!(decode_data_url("data:image/png,plaintext").is_none());

Parameters:

Name	Type	Required	Description
url	String	Yes	The URL to fetch

Returns: Option<DecodedDataUrl>

---

register_custom_provider()

Register a custom provider in the global runtime registry.

The provider will be checked before all built-in providers during model detection. If a provider with the same name already exists it is replaced.

Errors:

Returns an error if the config is invalid (empty name, empty base_url, or no model prefixes).

Signature:

pub fn register_custom_provider(config: CustomProviderConfig) -> Result<(), LiterLlmError>

Example:

register_custom_provider(CustomProviderConfig::default())?;

Parameters:

Name	Type	Required	Description
config	CustomProviderConfig	Yes	The configuration options

Returns: No return value.

Errors: Returns Err(LiterLlmError).

---

unregister_custom_provider()

Remove a previously registered custom provider by name.

Returns true if a provider with the given name was found and removed, false if no such provider existed.

Errors:

Returns an error if the custom-provider registry cannot be updated.

Signature:

pub fn unregister_custom_provider(name: &str) -> Result<bool, LiterLlmError>

Example:

let result = unregister_custom_provider("value")?;

Parameters:

Name	Type	Required	Description
name	String	Yes	The name

Returns: bool

Errors: Returns Err(LiterLlmError).

---

capabilities()

Return the capability flags for a named provider.

Performs an O(n) linear scan over the embedded registry (165 entries). Returns an owned value so bindings can pass capability data without borrowing registry internals.

For unknown provider_name values the function returns an all-false sentinel so callers never need to handle Option.

Signature:

pub fn capabilities(provider_name: &str) -> ProviderCapabilities

Example:

let result = capabilities("value");

Parameters:

Name	Type	Required	Description
provider_name	String	Yes	The provider name

Returns: ProviderCapabilities

---

all_providers()

Return all provider configs from the registry.

Useful for tooling, documentation generation, or runtime enumeration. Returns the public ProviderConfig slice (without capability flags). To query capability flags for a specific provider use capabilities.

Signature:

pub fn all_providers() -> Result<Vec<ProviderConfig>, LiterLlmError>

Example:

let result = all_providers()?;

Returns: Vec<ProviderConfig>

Errors: Returns Err(LiterLlmError).

---

complex_provider_names()

Return the set of complex provider names.

Complex providers require custom auth/routing logic beyond simple bearer tokens (e.g. AWS Bedrock SigV4, Vertex AI OAuth2).

The returned reference points into the static registry — no allocation.

Signature:

pub fn complex_provider_names() -> Result<Vec<String>, LiterLlmError>

Example:

let result = complex_provider_names()?;

Returns: Vec<String>

Errors: Returns Err(LiterLlmError).

---

completion_cost()

Calculate the estimated cost of a completion given a model name and token counts.

Returns None if the model is not present in the embedded pricing registry. Returns Some(cost_usd) otherwise, where the value is in US dollars.

When an exact model name match is not found, progressively shorter prefixes are tried by stripping from the last - or . separator. For example, gpt-4-0613 will match gpt-4 if no gpt-4-0613 entry exists.

Signature:

pub fn completion_cost(model: &str, prompt_tokens: u64, completion_tokens: u64) -> Option<f64>

Example:

use liter_llm::cost;

let usd = cost::completion_cost("gpt-4o", 1_000, 500).expect("gpt-4o is a known model");
// 1000 * 0.0000025 + 500 * 0.00001 = 0.0025 + 0.005 = 0.0075
assert!((usd - 0.0075).abs() < 1e-9);

Parameters:

Name	Type	Required	Description
model	String	Yes	The model
prompt_tokens	u64	Yes	The prompt tokens
completion_tokens	u64	Yes	The completion tokens

Returns: Option<f64>

---

completion_cost_with_cache()

Calculate the estimated cost of a completion, accounting for cached (cache-hit) prompt tokens billed at the provider’s discounted rate.

cached_tokens is the count of prompt tokens served from the provider’s prompt cache. It must be <= prompt_tokens (cached tokens are a subset of the prompt). The non-cached portion is billed at input_cost_per_token and the cached portion at cache_read_input_token_cost when the model has cache pricing; otherwise the entire prompt is billed at the regular input rate.

Returns None if the model is not present in the embedded pricing registry, mirroring completion_cost.

When the model has ModelPricing::tiers, the tier whose min_context_tokens is the highest value <= prompt_tokens supplies the input/output/cache rates for the whole call; models without tiers (or when prompt_tokens is below every tier threshold) use the base rates unchanged, matching the original flat-rate behaviour.

Signature:

pub fn completion_cost_with_cache(model: &str, prompt_tokens: u64, cached_tokens: u64, completion_tokens: u64) -> Option<f64>

Example:

let result = completion_cost_with_cache("value", 42, 42, 42);

Parameters:

Name	Type	Required	Description
model	String	Yes	The model
prompt_tokens	u64	Yes	The prompt tokens
cached_tokens	u64	Yes	The cached tokens
completion_tokens	u64	Yes	The completion tokens

Returns: Option<f64>

---

model_info()

Look up FFI-friendly pricing and capability metadata for a model.

Returns None if the model is not present in the active pricing registry. Uses the same exact-match-then-prefix-fallback resolution as model_pricing; unlike model_pricing, the result is an owned ModelInfo value safe to hand across the FFI boundary.

When a runtime catalog refresh has succeeded, this reflects the refreshed (overlay) catalog; otherwise it reflects the embedded catalog. See model_pricing for the embedded-only alternative.

Signature:

pub fn model_info(model: &str) -> Option<ModelInfo>

Example:

let result = model_info("value");

Parameters:

Name	Type	Required	Description
model	String	Yes	The model

Returns: Option<ModelInfo>

---

clear()

Remove all guardrails from the global registry.

Primarily useful in tests to reset state between test cases.

Panics:

Panics if the global registry lock is poisoned.

Signature:

pub fn clear()

Example:

clear();

Returns: No return value.

---

count_tokens()

Count tokens in a text string using the tokenizer for the given model.

The tokenizer is resolved from the model name prefix (e.g. "gpt-4o" maps to the Xenova/gpt-4o HuggingFace tokenizer). Tokenizers are cached after first load.

Errors:

Returns LiterLlmError::BadRequest if the tokenizer cannot be loaded (e.g. network failure on first use) or if tokenization itself fails.

Signature:

pub fn count_tokens(model: &str, text: &str) -> Result<usize, LiterLlmError>

Example:

let result = count_tokens("value", "value")?;

Parameters:

Name	Type	Required	Description
model	String	Yes	The model
text	String	Yes	The text

Returns: usize

Errors: Returns Err(LiterLlmError).

---

count_request_tokens()

Count tokens for a full ChatCompletionRequest.

Sums tokens across all message text contents plus a per-message overhead of ~4 tokens (for role, separators, and formatting metadata). Tool definitions and multimodal content parts (images, audio, documents) are not counted — only textual content contributes to the token total.

Errors:

Returns LiterLlmError::BadRequest if the tokenizer cannot be loaded or if tokenization fails for any message.

Signature:

pub fn count_request_tokens(model: &str, req: ChatCompletionRequest) -> Result<usize, LiterLlmError>

Example:

let result = count_request_tokens("value", ChatCompletionRequest::default())?;

Parameters:

Name	Type	Required	Description
model	String	Yes	The model
req	ChatCompletionRequest	Yes	The chat completion request

Returns: usize

Errors: Returns Err(LiterLlmError).

---

check_bound()

Assert that current_len + incoming does not exceed limit.

Call this before appending incoming bytes to any buffer that must stay below limit. Returns Err(LiterLlmError::Streaming) on overflow and emits a tracing::warn! with context.

Signature:

pub fn check_bound(context: &str, current_len: usize, incoming: usize, limit: usize) -> Result<(), LiterLlmError>

Example:

check_bound("SSE buffer", buffer.len(), chunk.len(), SSE_BUFFER_MAX_BYTES)?;
buffer.push_str(chunk_str);

Parameters:

Name	Type	Required	Description
context	String	Yes	The context
current_len	usize	Yes	The current len
incoming	usize	Yes	The incoming
limit	usize	Yes	The limit

Returns: No return value.

Errors: Returns Err(LiterLlmError).

---

ensure_crypto_provider()

Install the ring crypto provider as the rustls process default, idempotently.

rustls 0.23+ removed the implicit default provider. This function installs ring once per process. Subsequent calls are no-ops. Calling it after another rustls crypto provider has already been installed is safe: the Err from install_default() is silently ignored.

Called automatically by every internal reqwest::Client constructor (auth providers, default HTTP client). Bindings and downstream consumers reach those constructors transitively, so no manual init is required.

WASM builds are exempt — the WASM target uses the browser/Node.js fetch API instead of rustls, so no crypto provider is needed.

Windows builds use native-tls (SChannel) via reqwest, so rustls is not present and no crypto provider installation is needed.

Signature:

pub fn ensure_crypto_provider()

Example:

ensure_crypto_provider();

Returns: No return value.

---

ensure_crypto_provider()

No-op on Windows: reqwest uses native-tls (SChannel), so no rustls provider installation is needed. All callers use the same call site regardless of platform.

Signature:

pub fn ensure_crypto_provider()

Example:

ensure_crypto_provider();

Returns: No return value.

---

install_catalog_overlay_from_str()

Install the overlay registry from a raw catalog JSON string, bypassing the network and disk cache entirely.

Parses and flattens catalog_json with the same registry_from_catalog_str logic used for the embedded catalog and the network refresh path, then atomically swaps it in as the active overlay. A parse failure returns CatalogRefreshError::Parse and leaves any existing overlay untouched.

This is primarily a testable seam: it lets tests exercise overlay installation and the embedded/overlay fallback behavior in completion_cost / model_info without a real network call.

Signature:

pub fn install_catalog_overlay_from_str(catalog_json: &str) -> Result<(), CatalogRefreshError>

Example:

install_catalog_overlay_from_str("value")?;

Parameters:

Name	Type	Required	Description
catalog_json	String	Yes	The catalog json

Returns: No return value.

Errors: Returns Err(CatalogRefreshError).

---

clear_catalog_overlay()

Clear the overlay registry, reverting completion_cost, completion_cost_with_cache, and model_info to the embedded catalog.

Primarily a test seam (see install_catalog_overlay_from_str); also usable by long-running processes that want to abandon a runtime refresh.

Signature:

pub fn clear_catalog_overlay()

Example:

clear_catalog_overlay();

Returns: No return value.

---

refresh_catalog()

Refresh the runtime catalog overlay per config.

• config.enabled == false: returns Ok(RefreshOutcome::Disabled) immediately. No network, filesystem, or overlay activity.

• A fresh on-disk cache (age < config.ttl_seconds) exists at the resolved cache path (config.cache_path, or a default under std::env::temp_dir()): read + flatten it and install the overlay, returning Ok(RefreshOutcome::FromCache). No network request is made.

• Otherwise: validate config.source_url uses https (CatalogRefreshError::InsecureUrl otherwise), fetch it, flatten it, install the overlay, best-effort write the raw JSON to the cache path (a cache write failure does not fail the refresh), and return Ok(RefreshOutcome::Fetched).

On any error return, the overlay is left untouched: the previously active registry (a prior successful overlay, or the embedded catalog if none was ever installed) remains in effect. This is what makes the feature air-gap-safe — an unreachable or invalid source_url never degrades completion_cost / model_info below embedded-catalog availability.

Signature:

pub async fn refresh_catalog(config: CatalogRefreshConfig) -> Result<RefreshOutcome, CatalogRefreshError>

Example:

let result = refresh_catalog(CatalogRefreshConfig::default()).await?;

Parameters:

Name	Type	Required	Description
config	CatalogRefreshConfig	Yes	The configuration options

Returns: RefreshOutcome

Errors: Returns Err(CatalogRefreshError).

---

Types

AssistantMessage

Assistant’s response to a user message.

Field	Type	Default	Description
content	Option<AssistantContent>	Default::default()	The assistant’s response: plain text, structured parts, or absent. None is valid when the model replies with tool calls only.
name	Option<String>	Default::default()	Optional name for the assistant.
tool_calls	Option<Vec<ToolCall>>	vec!\[\]	Tool calls the model wants to execute, if any.
refusal	Option<String>	Default::default()	Refusal reason, if the model declined to respond per safety policies.
function_call	Option<FunctionCall>	Default::default()	Deprecated legacy function_call field; retained for API compatibility.
reasoning_content	Option<String>	Default::default()	Reasoning/thinking tokens returned by the provider, if any (e.g. DeepSeek R1, Qwen reasoning_content, or Anthropic extended thinking).

Methods

text()

Return the assistant’s textual response, concatenating all Text parts if the content is structured.

Returns None for Refusal-only or OutputImage-only responses.

Signature:

pub fn text(&self) -> Option<String>

Example:

let result = instance.text();

Returns: Option<String>

refusal_text()

Return the refusal message, if the model declined to respond.

Checks both the top-level refusal field and any Refusal parts inside a structured content.

Signature:

pub fn refusal_text(&self) -> Option<String>

Example:

let result = instance.refusal_text();

Returns: Option<String>

reasoning_text()

Return the model’s reasoning/thinking tokens, if the provider returned any.

Signature:

pub fn reasoning_text(&self) -> Option<String>

Example:

let result = instance.reasoning_text();

Returns: Option<String>

output_images()

Return all AssistantPart::OutputImage parts in the response.

Signature:

pub fn output_images(&self) -> Vec<ImageUrl>

Example:

let result = instance.output_images();

Returns: Vec<ImageUrl>

output_audio()

Return all AssistantPart::OutputAudio parts in the response.

Signature:

pub fn output_audio(&self) -> Vec<AudioContent>

Example:

let result = instance.output_audio();

Returns: Vec<AudioContent>

---

AudioContent

Audio content part for speech-capable models.

Field	Type	Default	Description
data	String	—	Base64-encoded audio data.
format	String	—	Audio format (e.g., “wav”, “mp3”, “ogg”).

---

AuthConfig

Auth configuration block.

Field	Type	Default	Description
auth_type	AuthType	—	Auth scheme classification.
env_var	Option<String>	None	Name of the environment variable that holds the API key (e.g. "OPENAI_API_KEY"). Holds the variable name, never the secret value.

---

BatchListQuery

Query parameters for listing batches.

Field	Type	Default	Description
limit	Option<u32>	Default::default()	Maximum number of results to return. Defaults to 20.
after	Option<String>	Default::default()	Pagination cursor: return results after this batch ID.

---

BatchListResponse

Response from listing batches.

Field	Type	Default	Description
object	String	—	Object type (always "list").
data	Vec<BatchObject>	vec!\[\]	List of batch objects.
has_more	Option<bool>	Default::default()	Whether more results are available.
first_id	Option<String>	Default::default()	First batch ID in the result set (for pagination).
last_id	Option<String>	Default::default()	Last batch ID in the result set (for pagination).

---

BatchObject

A batch job object.

Field	Type	Default	Description
id	String	—	Unique batch ID.
object	String	—	Object type (always "batch").
endpoint	String	—	API endpoint (e.g., "/v1/chat/completions").
input_file_id	String	—	ID of the input file.
completion_window	String	—	Completion window (e.g., "24h").
status	BatchStatus	BatchStatus::Validating	Current job status.
output_file_id	Option<String>	Default::default()	ID of the output file (present when completed).
error_file_id	Option<String>	Default::default()	ID of the error file (present if some requests failed).
created_at	u64	—	Unix timestamp of batch creation.
completed_at	Option<u64>	Default::default()	Unix timestamp of completion (if completed).
failed_at	Option<u64>	Default::default()	Unix timestamp of failure (if failed).
expired_at	Option<u64>	Default::default()	Unix timestamp of expiration (if expired).
request_counts	Option<BatchRequestCounts>	Default::default()	Request processing counts.
metadata	Option<serde_json::Value>	Default::default()	Metadata attached to the batch.

---

BatchRequestCounts

Request processing counts for a batch.

Field	Type	Default	Description
total	u64	—	Total requests in the batch.
completed	u64	—	Completed requests.
failed	u64	—	Failed requests.

---

BedrockConfig

AWS Bedrock configuration.

All fields are optional; anything left unset falls back to the standard AWS environment variables (AWS_DEFAULT_REGION / AWS_REGION, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN, BEDROCK_CROSS_REGION).

Field	Type	Default	Description
region	Option<String>	Default::default()	AWS region (e.g. "us-east-1").
cross_region_prefix	Option<String>	Default::default()	Cross-region inference profile prefix (e.g. "us").
access_key_id	Option<String>	Default::default()	Explicit AWS access key ID.
secret_access_key	Option<String>	Default::default()	Explicit AWS secret access key.
session_token	Option<String>	Default::default()	Explicit AWS session token (temporary credentials).

---

BudgetConfig

Configuration for budget enforcement.

Field	Type	Default	Description
global_limit	Option<f64>	None	Maximum total spend across all models, in USD. None means unlimited.
model_limits	HashMap<String, f64>	HashMap::new()	Per-model spending limits in USD. Models not listed here are only constrained by global_limit.
enforcement	Enforcement	Enforcement::Hard	Whether to reject requests or merely warn when a limit is exceeded.

Methods

default()

Signature:

pub fn default() -> BudgetConfig

Example:

let result = BudgetConfig::default();

Returns: BudgetConfig

---

CacheConfig

Configuration for the response cache.

Field	Type	Default	Description
max_entries	usize	256	Maximum number of cached entries.
ttl	std::time::Duration	300000ms	Time-to-live for each cached entry.
backend	CacheBackend	CacheBackend::Memory	Storage backend to use.

Methods

default()

Signature:

pub fn default() -> CacheConfig

Example:

let result = CacheConfig::default();

Returns: CacheConfig

---

CatalogRefreshConfig

Plain-data configuration for refresh_catalog.

Deliberately FFI/binding-friendly: no Duration or PathBuf, just primitives that translate directly across language boundaries.

Field	Type	Default	Description
enabled	bool	false	Runtime catalog refresh is entirely opt-in: when false, refresh_catalog is a no-op that returns Ok(RefreshOutcome::Disabled) without touching the network, the filesystem, or the overlay registry.
source_url	String	—	Source URL to fetch catalog.json from. Must be https. Defaults to DEFAULT_CATALOG_URL; configurable so self-hosted mirrors work.
ttl_seconds	u64	86400	How long a cached catalog.json remains valid before a network refetch is attempted, in seconds.
cache_path	Option<String>	None	Filesystem path for the on-disk cache. None uses a default path under std::env::temp_dir().

Methods

default()

Signature:

pub fn default() -> CatalogRefreshConfig

Example:

let result = CatalogRefreshConfig::default();

Returns: CatalogRefreshConfig

---

ChatCompletionChunk

A streamed chunk of a chat completion response.

Field	Type	Default	Description
id	String	—	Unique identifier for this stream.
object	String	—	Always "chat.completion.chunk" from OpenAI-compatible APIs. Stored as a plain String so non-standard provider values do not fail parsing.
created	u64	—	Unix timestamp of chunk creation.
model	String	—	Model used to generate the chunk.
choices	Vec<StreamChoice>	vec!\[\]	Streaming choices (delta updates).
usage	Option<Usage>	Default::default()	Token usage (typically only in the final chunk).
system_fingerprint	Option<String>	Default::default()	Fingerprint of the system configuration (OpenAI-specific).
service_tier	Option<String>	Default::default()	Service tier used (OpenAI-specific).

---

ChatCompletionRequest

Chat completion request (compatible with OpenAI and similar APIs).

Field	Type	Default	Description
model	String	—	Model ID (e.g., "gpt-4o-mini", "claude-3-5-sonnet").
messages	Vec<Message>	vec!\[\]	Conversation history from oldest to newest.
temperature	Option<f64>	Default::default()	Sampling temperature in \[0.0, 2.0\]. Higher increases randomness. Defaults to 1.0.
top_p	Option<f64>	Default::default()	Nucleus sampling parameter in \[0.0, 1.0\]. Lower is more focused.
n	Option<u32>	Default::default()	Number of chat completions to generate. Defaults to 1.
stream	Option<bool>	Default::default()	Whether to stream the response. Managed by the client layer — do not set directly.
stop	Option<StopSequence>	Default::default()	Stop sequence(s) that halt token generation.
max_tokens	Option<u64>	Default::default()	Max output tokens. Different from max_completion_tokens in some providers.
presence_penalty	Option<f64>	Default::default()	Presence penalty in \[-2.0, 2.0\]. Positive discourages repeated topics.
frequency_penalty	Option<f64>	Default::default()	Frequency penalty in \[-2.0, 2.0\]. Positive discourages repeated tokens.
logit_bias	Option<HashMap<String, f64>>	HashMap::new()	Token bias map. Uses BTreeMap (sorted keys) for deterministic serialization order — important when hashing or signing requests.
user	Option<String>	Default::default()	User identifier for request tracking and abuse detection.
tools	Option<Vec<ChatCompletionTool>>	vec!\[\]	Tools the model can invoke.
tool_choice	Option<ToolChoice>	Default::default()	Tool usage mode (auto, required, none, or specific tool).
parallel_tool_calls	Option<bool>	Default::default()	Whether the model can call multiple tools in parallel. Defaults to true.
response_format	Option<ResponseFormat>	Default::default()	Output format constraint (text, JSON, JSON schema).
stream_options	Option<StreamOptions>	Default::default()	Streaming options (e.g., include_usage).
seed	Option<i64>	Default::default()	Random seed for reproducible outputs. Provider support varies.
reasoning_effort	Option<ReasoningEffort>	Default::default()	Reasoning effort level (minimal, low, medium, high, max) for extended-thinking models.
modalities	Option<Vec<Modality>>	vec!\[\]	Output modalities to request from the model. For OpenAI audio models, pass \["text", "audio"\]. Vertex AI / Gemini translates these to generationConfig.responseModalities (uppercase).
extra_body	Option<serde_json::Value>	Default::default()	Provider-specific extra parameters merged into the request body. Use for guardrails, safety settings, grounding config, etc.

---

ChatCompletionResponse

Chat completion response from the API.

Field	Type	Default	Description
id	String	—	Unique identifier for this response.
object	String	—	Always "chat.completion" from OpenAI-compatible APIs. Stored as a plain String so non-standard provider values do not break deserialization.
created	u64	—	Unix timestamp of response creation.
model	String	—	Model used to generate the response.
choices	Vec<Choice>	vec!\[\]	List of completion choices.
usage	Option<Usage>	Default::default()	Token usage statistics.
system_fingerprint	Option<String>	Default::default()	Fingerprint of the system configuration (OpenAI-specific).
service_tier	Option<String>	Default::default()	Service tier used (OpenAI-specific).

---

ChatCompletionTool

A tool the model can invoke (currently, all tools are functions).

Field	Type	Default	Description
tool_type	ToolType	—	Tool type (always “function” in OpenAI spec).
function	FunctionDefinition	—	Function definition with name, description, and JSON schema parameters.

---

Choice

A single completion choice.

Field	Type	Default	Description
index	u32	—	Index of this choice in the choices array.
message	AssistantMessage	—	The assistant’s message response.
finish_reason	Option<FinishReason>	Default::default()	Why the model stopped generating (stop, length, tool_calls, content_filter, etc.).

---

ChunkMiddleware

A per-chunk transformation in the StreamPipeline.

Each middleware receives a typed chunk and returns Ok(Some(chunk)) to pass it through (optionally modified), Ok(None) to drop the chunk, or Err(e) to propagate a stream error.

The trait is object-safe so multiple middleware implementations can be chained inside StreamPipeline.

Methods

process()

Process a single chunk.

• Ok(Some(chunk)) — emit (possibly transformed) chunk.
• Ok(None) — drop this chunk silently.
• Err(e) — propagate as a stream error.

Signature:

pub fn process(&self, chunk: ChatCompletionChunk) -> Result<Option<ChatCompletionChunk>, LiterLlmError>

Example:

let result = instance.process(ChatCompletionChunk::default())?;

Parameters:

Name	Type	Required	Description
chunk	ChatCompletionChunk	Yes	The chat completion chunk

Returns: Option<ChatCompletionChunk>

Errors: Returns Err(LiterLlmError).

---

CreateBatchRequest

Request to create a batch job.

Field	Type	Default	Description
input_file_id	String	—	ID of the uploaded input file (JSONL format).
endpoint	String	—	API endpoint (e.g., "/v1/chat/completions").
completion_window	String	—	Completion window (e.g., "24h").
metadata	Option<serde_json::Value>	Default::default()	Optional metadata to attach to the batch.

---

CreateFileRequest

Request to upload a file.

Field	Type	Default	Description
file	String	—	Base64-encoded file data.
purpose	FilePurpose	FilePurpose::Assistants	Purpose for the file.
filename	Option<String>	Default::default()	Optional filename to associate with the upload.

---

CreateImageRequest

Request to create images from a text prompt.

Field	Type	Default	Description
prompt	String	—	Text description of the image to generate.
model	Option<String>	Default::default()	Model ID (e.g., "dall-e-3"). Optional; API may use default if unset.
n	Option<u32>	Default::default()	Number of images to generate. Defaults to 1.
size	Option<String>	Default::default()	Image size (e.g., "1024x1024", "1792x1024").
quality	Option<String>	Default::default()	Image quality: "standard" or "hd".
style	Option<String>	Default::default()	Style: "natural" or "vivid" (DALL-E 3 only).
response_format	Option<String>	Default::default()	Response format: "url" or "b64_json".
user	Option<String>	Default::default()	User identifier for request tracking.

---

CreateResponseRequest

Request to create a structured response.

Field	Type	Default	Description
model	String	—	Model ID.
input	serde_json::Value	—	Input data to process (e.g., a document to extract from).
instructions	Option<String>	Default::default()	Instructions for processing the input.
tools	Option<Vec<ResponseTool>>	vec!\[\]	Available tools the model can use.
temperature	Option<f64>	Default::default()	Sampling temperature in \[0.0, 2.0\]. Defaults to 1.0.
max_output_tokens	Option<u64>	Default::default()	Maximum output tokens.
metadata	Option<serde_json::Value>	Default::default()	Optional metadata.
stream	Option<bool>	Default::default()	Whether to stream the response. Managed by the client layer — do not set directly.

---

CreateSpeechRequest

Request to generate speech audio from text.

Field	Type	Default	Description
model	String	—	Model ID (e.g., "tts-1", "tts-1-hd").
input	String	—	Text to synthesize into speech.
voice	String	—	Voice name (e.g., "alloy", "echo", "fable", "onyx", "nova", "shimmer").
response_format	Option<String>	Default::default()	Audio format (e.g., "mp3", "opus", "aac", "flac", "wav", "pcm").
speed	Option<f64>	Default::default()	Playback speed in \[0.25, 4.0\]. Defaults to 1.0.

---

CreateTranscriptionRequest

Request to transcribe audio into text.

Field	Type	Default	Description
model	String	—	Model ID (e.g., "whisper-1").
file	String	—	Base64-encoded audio file data.
language	Option<String>	Default::default()	Language ISO-639-1 code (e.g., "en", "fr", "de"). Optional; model auto-detects.
prompt	Option<String>	Default::default()	Optional text to guide the model (improves accuracy for domain-specific terms).
response_format	Option<String>	Default::default()	Output format (e.g., "json", "text", "vtt", "srt", "verbose_json").
temperature	Option<f64>	Default::default()	Sampling temperature in \[0.0, 1.0\]. Higher increases variability. Defaults to 0.

---

CustomProviderConfig

Configuration for registering a custom LLM provider at runtime.

Field	Type	Default	Description
name	String	—	Unique name for this provider (e.g., “my-provider”).
base_url	String	—	Base URL for the provider’s API (e.g., <https://api.my-provider.com/v1>).
auth_header	AuthHeaderFormat	—	Authentication header format.
model_prefixes	Vec<String>	—	Model name prefixes that route to this provider (e.g., \["my-"\]).

---

DecodedDataUrl

Result of decoding a data: URL — MIME type and the decoded byte payload.

Named struct (rather than a tuple) so polyglot bindings can extract decode_data_url with a typed return rather than a sanitized scalar.

Field	Type	Default	Description
mime	String	—	MIME type extracted from the URL prefix (verbatim, not normalised).
data	Vec<u8>	—	Decoded base64 payload.

---

DefaultClient

Default client implementation backed by reqwest.

Sends requests to 165 LLM providers with automatic provider detection and per-request routing. The provider is resolved at construction time from model_hint (or defaults to OpenAI), but individual requests can override the provider via model name prefix (e.g. "anthropic/claude-3-5-sonnet" routes to Anthropic regardless of construction-time setting).

When the model prefix does not match any known provider, the construction-time provider is used as the fallback. This enables seamless migration between providers by changing only the model name.

The provider is stored behind an Arc so it can be shared cheaply into async closures and streaming tasks. Pre-computed auth headers and extra headers are cached at construction to avoid redundant encoding on every request.

Methods

chat()

Signature:

pub async fn chat(&self, req: ChatCompletionRequest) -> Result<ChatCompletionResponse, LiterLlmError>

Example:

let result = instance.chat(ChatCompletionRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	ChatCompletionRequest	Yes	The chat completion request

Returns: ChatCompletionResponse

Errors: Returns Err(LiterLlmError).

chat_stream()

Signature:

fn chat_stream(&self, req: ChatCompletionRequest) -> BoxFuture<'_, Result<BoxStream<'static, Result<ChatCompletionChunk>>>>

Example:

let mut stream = instance.chat_stream(ChatCompletionRequest::default()).await?;
while let Some(chunk) = stream.next().await {
    let chunk = chunk?;
    println!("{chunk:?}");
}

Parameters:

Name	Type	Required	Description
req	ChatCompletionRequest	Yes	The chat completion request

Returns: BoxFuture<'_, Result<BoxStream<'static, Result<ChatCompletionChunk>>>>

Errors: Returns Err(LiterLlmError).

embed()

Signature:

pub async fn embed(&self, req: EmbeddingRequest) -> Result<EmbeddingResponse, LiterLlmError>

Example:

let result = instance.embed(EmbeddingRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	EmbeddingRequest	Yes	The embedding request

Returns: EmbeddingResponse

Errors: Returns Err(LiterLlmError).

list_models()

Signature:

pub async fn list_models(&self) -> Result<ModelsListResponse, LiterLlmError>

Example:

let result = instance.list_models().await?;

Returns: ModelsListResponse

Errors: Returns Err(LiterLlmError).

image_generate()

Signature:

pub async fn image_generate(&self, req: CreateImageRequest) -> Result<ImagesResponse, LiterLlmError>

Example:

let result = instance.image_generate(CreateImageRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	CreateImageRequest	Yes	The create image request

Returns: ImagesResponse

Errors: Returns Err(LiterLlmError).

speech()

Signature:

pub async fn speech(&self, req: CreateSpeechRequest) -> Result<Vec<u8>, LiterLlmError>

Example:

let result = instance.speech(CreateSpeechRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	CreateSpeechRequest	Yes	The create speech request

Returns: Vec<u8>

Errors: Returns Err(LiterLlmError).

transcribe()

Signature:

pub async fn transcribe(&self, req: CreateTranscriptionRequest) -> Result<TranscriptionResponse, LiterLlmError>

Example:

let result = instance.transcribe(CreateTranscriptionRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	CreateTranscriptionRequest	Yes	The create transcription request

Returns: TranscriptionResponse

Errors: Returns Err(LiterLlmError).

moderate()

Signature:

pub async fn moderate(&self, req: ModerationRequest) -> Result<ModerationResponse, LiterLlmError>

Example:

let result = instance.moderate(ModerationRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	ModerationRequest	Yes	The moderation request

Returns: ModerationResponse

Errors: Returns Err(LiterLlmError).

rerank()

Signature:

pub async fn rerank(&self, req: RerankRequest) -> Result<RerankResponse, LiterLlmError>

Example:

let result = instance.rerank(RerankRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	RerankRequest	Yes	The rerank request

Returns: RerankResponse

Errors: Returns Err(LiterLlmError).

search()

Signature:

pub async fn search(&self, req: SearchRequest) -> Result<SearchResponse, LiterLlmError>

Example:

let result = instance.search(SearchRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	SearchRequest	Yes	The search request

Returns: SearchResponse

Errors: Returns Err(LiterLlmError).

ocr()

Signature:

pub async fn ocr(&self, req: OcrRequest) -> Result<OcrResponse, LiterLlmError>

Example:

let result = instance.ocr(OcrRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	OcrRequest	Yes	The ocr request

Returns: OcrResponse

Errors: Returns Err(LiterLlmError).

create_file()

Signature:

pub async fn create_file(&self, req: CreateFileRequest) -> Result<FileObject, LiterLlmError>

Example:

let result = instance.create_file(CreateFileRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	CreateFileRequest	Yes	The create file request

Returns: FileObject

Errors: Returns Err(LiterLlmError).

retrieve_file()

Signature:

pub async fn retrieve_file(&self, file_id: &str) -> Result<FileObject, LiterLlmError>

Example:

let result = instance.retrieve_file("value").await?;

Parameters:

Name	Type	Required	Description
file_id	String	Yes	The file id

Returns: FileObject

Errors: Returns Err(LiterLlmError).

delete_file()

Signature:

pub async fn delete_file(&self, file_id: &str) -> Result<DeleteResponse, LiterLlmError>

Example:

let result = instance.delete_file("value").await?;

Parameters:

Name	Type	Required	Description
file_id	String	Yes	The file id

Returns: DeleteResponse

Errors: Returns Err(LiterLlmError).

list_files()

Signature:

pub async fn list_files(&self, query: Option<FileListQuery>) -> Result<FileListResponse, LiterLlmError>

Example:

let result = instance.list_files(FileListQuery::default()).await?;

Parameters:

Name	Type	Required	Description
query	Option<FileListQuery>	No	The file list query

Returns: FileListResponse

Errors: Returns Err(LiterLlmError).

file_content()

Signature:

pub async fn file_content(&self, file_id: &str) -> Result<Vec<u8>, LiterLlmError>

Example:

let result = instance.file_content("value").await?;

Parameters:

Name	Type	Required	Description
file_id	String	Yes	The file id

Returns: Vec<u8>

Errors: Returns Err(LiterLlmError).

create_batch()

Signature:

pub async fn create_batch(&self, req: CreateBatchRequest) -> Result<BatchObject, LiterLlmError>

Example:

let result = instance.create_batch(CreateBatchRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	CreateBatchRequest	Yes	The create batch request

Returns: BatchObject

Errors: Returns Err(LiterLlmError).

retrieve_batch()

Signature:

pub async fn retrieve_batch(&self, batch_id: &str) -> Result<BatchObject, LiterLlmError>

Example:

let result = instance.retrieve_batch("value").await?;

Parameters:

Name	Type	Required	Description
batch_id	String	Yes	The batch id

Returns: BatchObject

Errors: Returns Err(LiterLlmError).

list_batches()

Signature:

pub async fn list_batches(&self, query: Option<BatchListQuery>) -> Result<BatchListResponse, LiterLlmError>

Example:

let result = instance.list_batches(BatchListQuery::default()).await?;

Parameters:

Name	Type	Required	Description
query	Option<BatchListQuery>	No	The batch list query

Returns: BatchListResponse

Errors: Returns Err(LiterLlmError).

cancel_batch()

Signature:

pub async fn cancel_batch(&self, batch_id: &str) -> Result<BatchObject, LiterLlmError>

Example:

let result = instance.cancel_batch("value").await?;

Parameters:

Name	Type	Required	Description
batch_id	String	Yes	The batch id

Returns: BatchObject

Errors: Returns Err(LiterLlmError).

fetch_batch_for_polling()

Signature:

pub async fn fetch_batch_for_polling(&self, batch_id: &str) -> Result<BatchObject, LiterLlmError>

Example:

let result = instance.fetch_batch_for_polling("value").await?;

Parameters:

Name	Type	Required	Description
batch_id	String	Yes	The batch id

Returns: BatchObject

Errors: Returns Err(LiterLlmError).

wait_for_batch()

Poll a batch until it reaches a terminal status (Completed, Failed, Expired, Cancelled).

Uses exponential backoff with configurable initial interval, maximum interval, and backoff multiplier. Optionally supports a timeout that aborts polling if exceeded.

Errors:

Returns BatchWaitError::Failed if the batch reaches a failure terminal status. Returns BatchWaitError::Timeout if the configured timeout is exceeded. Returns BatchWaitError::Client for underlying client errors.

Signature:

pub async fn wait_for_batch(&self, batch_id: &str, config: WaitForBatchConfig) -> Result<BatchObject, BatchWaitError>

Example:

# use liter_llm::client::{DefaultClient, ClientConfig, WaitForBatchConfig};
# async fn run() -> Result<(), Box<dyn std::error::Error>> {
let client = DefaultClient::new(ClientConfig::new("api-key"), None)?;
let batch = client.wait_for_batch("b-123", WaitForBatchConfig::default()).await?;
println!("Batch completed: {:?}", batch.status);
# Ok(())
# }

Parameters:

Name	Type	Required	Description
batch_id	String	Yes	The batch id
config	WaitForBatchConfig	Yes	The configuration options

Returns: BatchObject

Errors: Returns Err(BatchWaitError).

create_response()

Signature:

pub async fn create_response(&self, req: CreateResponseRequest) -> Result<ResponseObject, LiterLlmError>

Example:

let result = instance.create_response(CreateResponseRequest::default()).await?;

Parameters:

Name	Type	Required	Description
req	CreateResponseRequest	Yes	The create response request

Returns: ResponseObject

Errors: Returns Err(LiterLlmError).

retrieve_response()

Signature:

pub async fn retrieve_response(&self, response_id: &str) -> Result<ResponseObject, LiterLlmError>

Example:

let result = instance.retrieve_response("value").await?;

Parameters:

Name	Type	Required	Description
response_id	String	Yes	The response id

Returns: ResponseObject

Errors: Returns Err(LiterLlmError).

cancel_response()

Signature:

pub async fn cancel_response(&self, response_id: &str) -> Result<ResponseObject, LiterLlmError>

Example:

let result = instance.cancel_response("value").await?;

Parameters:

Name	Type	Required	Description
response_id	String	Yes	The response id

Returns: ResponseObject

Errors: Returns Err(LiterLlmError).

---

DeleteResponse

Response from a delete operation.

Field	Type	Default	Description
id	String	—	ID of the deleted resource.
object	String	—	Object type.
deleted	bool	—	Confirmation that the resource was deleted.

---

DeveloperMessage

Developer message (system-like message for Claude models).

Field	Type	Default	Description
content	String	—	Developer-specific instructions or context.
name	Option<String>	Default::default()	Optional name for the developer message source.

---

DocumentContent

PDF/document content part for vision-capable models.

Field	Type	Default	Description
data	String	—	Base64-encoded document data or URL.
media_type	String	—	MIME type (e.g., “application/pdf”, “text/csv”).

---

EmbeddingObject

A single embedding vector.

Field	Type	Default	Description
object	String	—	Always "embedding" from OpenAI-compatible APIs. Stored as a plain String so non-standard provider values do not break deserialization.
embedding	Vec<f32>	—	The embedding vector. Providers may return this as a JSON float array or, when encoding_format: "base64" was requested, as a base64 string of little-endian f32 bytes. Base64 responses are decoded on read; this field always serializes back out as a JSON float array.
index	u32	—	Index in the batch (corresponds to input order).

---

EmbeddingRequest

Embedding request.

Field	Type	Default	Description
model	String	—	Model ID (e.g., "text-embedding-3-small").
input	EmbeddingInput	EmbeddingInput::Single	Text or texts to embed.
encoding_format	Option<EmbeddingFormat>	Default::default()	Output format: float (native) or base64.
dimensions	Option<u32>	Default::default()	Requested embedding dimensions (if supported by the model).
user	Option<String>	Default::default()	User identifier for request tracking.

---

EmbeddingResponse

Embedding response.

Field	Type	Default	Description
object	String	—	Always "list" from OpenAI-compatible APIs. Stored as a plain String so non-standard provider values do not break deserialization.
data	Vec<EmbeddingObject>	—	List of embeddings.
model	String	—	Model used to generate embeddings.
usage	Option<Usage>	/* serde(default) */	Token usage (input tokens only; embeddings have zero output tokens).

---

FileListQuery

Query parameters for listing files.

Field	Type	Default	Description
purpose	Option<String>	Default::default()	Filter by file purpose (e.g., "batch", "fine-tune").
limit	Option<u32>	Default::default()	Maximum number of results to return. Defaults to 20.
after	Option<String>	Default::default()	Pagination cursor: return results after this file ID.

---

FileListResponse

Response from listing files.

Field	Type	Default	Description
object	String	—	Object type (always "list").
data	Vec<FileObject>	vec!\[\]	List of file objects.
has_more	Option<bool>	Default::default()	Whether more results are available.

---

FileObject

An uploaded file object.

Field	Type	Default	Description
id	String	—	Unique file ID.
object	String	—	Object type (always "file").
bytes	u64	—	File size in bytes.
created_at	u64	—	Unix timestamp of file creation.
filename	String	—	Filename.
purpose	String	—	File purpose.
status	Option<String>	Default::default()	Processing status (e.g., "uploaded", "processed").

---

FunctionCall

Function call details.

Field	Type	Default	Description
name	String	—	Function name.
arguments	String	—	Arguments as a JSON string (parse with serde_json::from_str).

---

FunctionDefinition

Function definition exposed to the model.

Field	Type	Default	Description
name	String	—	Name of the function. Required and must be alphanumeric + underscores.
description	Option<String>	/* serde(default) */	Human-readable description explaining what the function does.
parameters	Option<serde_json::Value>	/* serde(default) */	JSON Schema defining the function’s parameters.
strict	Option<bool>	/* serde(default) */	If true, enforce strict JSON schema validation for arguments.

---

FunctionMessage

Deprecated legacy function-role message body.

Field	Type	Default	Description
content	String	—	The extracted text content
name	String	—	The name

---

HealthChecker

Abstraction over a health probe strategy.

Implementors issue a lightweight probe against upstream (typically a provider base URL or named identifier) and report HealthStatus.

Methods

check()

Probe upstream and return its current HealthStatus.

The parameter is taken by value (String) so that implementations can move it into the returned future without a clone, making the 'static + Send bound on the future trivially satisfiable.

Signature:

pub async fn check(&self, upstream: &str) -> HealthStatus

Example:

let result = instance.check("value").await;

Parameters:

Name	Type	Required	Description
upstream	String	Yes	The upstream

Returns: HealthStatus

---

Image

A single generated image, returned as either a URL or base64 data.

Field	Type	Default	Description
url	Option<String>	Default::default()	Image URL (if response_format was “url”).
b64_json	Option<String>	Default::default()	Base64-encoded image data (if response_format was “b64_json”).
revised_prompt	Option<String>	Default::default()	The final prompt used to generate the image (DALL-E 3).

---

ImageUrl

An image URL reference with optional detail level for processing.

Field	Type	Default	Description
url	String	—	URL of the image (data URI or HTTP/HTTPS URL).
detail	Option<ImageDetail>	Default::default()	Detail level: low (512x512), high (2x2 tiles), or auto (model-selected).

---

ImagesResponse

Response containing generated images.

Field	Type	Default	Description
created	u64	—	Unix timestamp of image creation.
data	Vec<Image>	vec!\[\]	List of generated images.

---

IntentPrototype

An intent prototype: (intent_name, prototype_embedding, target_model_id).

Field	Type	Default	Description
name	String	—	Human-readable name for the intent (used in logs/metrics).
embedding	Vec<f64>	—	Pre-computed embedding vector for this intent.
model	String	—	Model to route to when this intent is detected.

---

JsonSchemaFormat

JSON Schema specification for constrained output.

Field	Type	Default	Description
name	String	—	Name of the schema (must be unique in the request).
description	Option<String>	Default::default()	Description of what the schema represents.
schema	serde_json::Value	—	JSON Schema object defining the output structure.
strict	Option<bool>	Default::default()	If true, enforce strict schema validation.

---

LlmBudgetConfig

Budget enforcement configuration.

Field	Type	Default	Description
global_limit	Option<f64>	Default::default()	Global spend limit in USD.
model_limits	Option<HashMap<String, f64>>	HashMap::new()	Per-model spend limits in USD, keyed by model name.
enforcement	Option<String>	Default::default()	Enforcement mode: "hard" (reject over-budget requests) or "soft" (log only).

---

LlmCacheConfig

Response cache configuration.

Field	Type	Default	Description
max_entries	Option<usize>	Default::default()	Maximum number of cached entries.
ttl_seconds	Option<u64>	Default::default()	Cache entry time-to-live, in seconds.
backend	Option<String>	Default::default()	Cache backend name (e.g. "memory", or an opendal scheme).
backend_config	Option<HashMap<String, String>>	HashMap::new()	Backend-specific configuration key/value pairs.

---

LlmConfig

Canonical configuration for an LLM client.

All fields except model are optional so that partially-specified configs (e.g. from environment-driven defaults) round-trip cleanly. Convert to a runtime client configuration via LlmConfig::into_client_builder.

temperature and max_tokens are request-time parameters rather than client-level settings; they are carried on this struct for callers to read when building individual requests, and are intentionally not mapped by LlmConfig::into_client_builder.

Field	Type	Default	Description
model	String	—	Model identifier (e.g. "gpt-4o", "bedrock/anthropic.claude-3-sonnet-20240229-v1:0").
api_key	Option<String>	Default::default()	API key for authentication.
base_url	Option<String>	Default::default()	Override base URL. When set, all requests go here and provider auto-detection is skipped.
timeout_secs	Option<u64>	Default::default()	Request timeout, in seconds.
max_retries	Option<u32>	Default::default()	Maximum number of retries on 429 / 5xx responses.
temperature	Option<f64>	Default::default()	Sampling temperature for requests built from this config.
max_tokens	Option<u64>	Default::default()	Maximum number of tokens to generate for requests built from this config.
load_env	Option<bool>	Default::default()	Automatically load the API key from the provider’s environment variable when no explicit key is provided (default: true).
headers	Option<HashMap<String, String>>	HashMap::new()	Extra headers sent on every request.
providers	Option<Vec<LlmProviderConfig>>	vec!\[\]	Custom provider configurations, in addition to the built-in providers.
cache	Option<LlmCacheConfig>	Default::default()	Response cache configuration.
budget	Option<LlmBudgetConfig>	Default::default()	Budget enforcement configuration.
rate_limit	Option<LlmRateLimitConfig>	Default::default()	Per-model rate limiting configuration.
cost_tracking	Option<bool>	Default::default()	Enable per-request cost tracking.
tracing	Option<bool>	Default::default()	Enable OpenTelemetry-compatible tracing spans.
cooldown_secs	Option<u64>	Default::default()	Cooldown duration after transient errors, in seconds.
health_check_secs	Option<u64>	Default::default()	Background health check interval, in seconds.
bedrock	Option<BedrockConfig>	Default::default()	AWS Bedrock configuration (region, credentials, cross-region routing).

Methods

providers()

Get the custom provider configurations from this config.

Signature:

pub fn providers(&self) -> Vec<LlmProviderConfig>

Example:

let result = instance.providers();

Returns: Vec<LlmProviderConfig>

---

LlmProviderConfig

A custom provider configuration entry.

Field	Type	Default	Description
name	String	—	Provider name, used to key model prefix matching.
base_url	String	—	Base URL for the provider’s OpenAI-compatible API.
auth_header	Option<String>	Default::default()	Header name used to carry the API key (defaults to Authorization when unset).
model_prefixes	Vec<String>	vec!\[\]	Model name prefixes routed to this provider (e.g. \["my-provider/"\]).

---

LlmRateLimitConfig

Per-model rate limiting configuration.

Field	Type	Default	Description
rpm	Option<u32>	Default::default()	Requests per minute limit.
tpm	Option<u64>	Default::default()	Tokens per minute limit.
window_seconds	Option<u64>	Default::default()	Rate limit window, in seconds.

---

ModelInfo

Public, FFI-friendly snapshot of a model’s pricing and capability metadata, projected from ModelPricing.

Unlike ModelPricing (which is excluded from binding generation), ModelInfo is an owned plain-data DTO safe to hand across the FFI boundary — see model_info.

Field	Type	Default	Description
input_cost_per_token	f64	—	Cost in USD per input (prompt) token.
output_cost_per_token	f64	—	Cost in USD per output (completion) token.
cache_read_input_token_cost	Option<f64>	Default::default()	Cost in USD per cached input token (cache hit / read).
cache_creation_input_token_cost	Option<f64>	Default::default()	Cost in USD per token written to the prompt cache.
input_cost_per_audio_token	Option<f64>	Default::default()	Cost in USD per input audio token.
output_cost_per_audio_token	Option<f64>	Default::default()	Cost in USD per output audio token.
output_cost_per_reasoning_token	Option<f64>	Default::default()	Cost in USD per reasoning (extended-thinking) output token.
max_tokens	Option<u64>	Default::default()	Total context window size in tokens (input + output).
max_input_tokens	Option<u64>	Default::default()	Maximum input (prompt) tokens accepted.
max_output_tokens	Option<u64>	Default::default()	Maximum output (completion) tokens the model can generate.
mode	Option<String>	Default::default()	Best-effort operating mode, e.g. "chat", "embedding".
supports_vision	Option<bool>	Default::default()	The model accepts image input.
supports_function_calling	Option<bool>	Default::default()	The model supports tool / function calling.
supports_reasoning	Option<bool>	Default::default()	The model supports extended-thinking / reasoning tokens.
supports_structured_output	Option<bool>	Default::default()	The model supports JSON-mode or response_format structured output.
supports_audio_input	Option<bool>	Default::default()	The model accepts audio input.
supports_audio_output	Option<bool>	Default::default()	The model can generate audio output.
supports_prompt_caching	Option<bool>	Default::default()	The model supports prompt caching.
tiers	Vec<ModelTier>	vec!\[\]	Context-tiered pricing overrides, sorted by ascending min_context_tokens. Empty when the model has flat pricing.

---

ModelObject

A model available from the API.

Field	Type	Default	Description
id	String	—	Model ID (e.g., "gpt-4o", "claude-3-5-sonnet").
object	String	—	Always "model" from OpenAI-compatible APIs. Stored as a plain String so non-standard provider values do not break deserialization. Defaults to empty when a provider omits the field.
created	u64	—	Unix timestamp of model creation (or release date). Defaults to 0 when a provider omits it — DeepSeek and some other OpenAI-compatible providers do not return created from /v1/models.
owned_by	String	—	Organization or entity that owns the model. Defaults to empty when a provider omits the field.

---

ModelTier

Public, FFI-friendly snapshot of a single context-window pricing tier, projected from PricingTier.

Field	Type	Default	Description
min_context_tokens	u64	—	The tier applies when the prompt/context token count is at least this value.
input_cost_per_token	f64	—	Cost in USD per input (prompt) token within this tier.
output_cost_per_token	f64	—	Cost in USD per output (completion) token within this tier.
cache_read_input_token_cost	Option<f64>	Default::default()	Cost in USD per cached input token within this tier.
cache_creation_input_token_cost	Option<f64>	Default::default()	Cost in USD per cache-write token within this tier.
input_cost_per_audio_token	Option<f64>	Default::default()	Cost in USD per input audio token within this tier.
output_cost_per_audio_token	Option<f64>	Default::default()	Cost in USD per output audio token within this tier.
output_cost_per_reasoning_token	Option<f64>	Default::default()	Cost in USD per reasoning output token within this tier.

---

ModelsListResponse

Response listing available models.

Field	Type	Default	Description
object	String	—	Always "list" from OpenAI-compatible APIs. Stored as a plain String so non-standard provider values do not break deserialization. Defaults to empty when a provider omits the field.
data	Vec<ModelObject>	vec!\[\]	List of available models.

---

ModerationCategories

Boolean flags for each moderation category.

Field	Type	Default	Description
sexual	bool	—	Sexual content.
hate	bool	—	Hate speech.
harassment	bool	—	Harassment.
self_harm	bool	—	Self-harm content.
sexual_minors	bool	—	Sexual content involving minors.
hate_threatening	bool	—	Hate speech that threatens violence.
violence_graphic	bool	—	Graphic violence.
self_harm_intent	bool	—	Intent to self-harm.
self_harm_instructions	bool	—	Instructions for self-harm.
harassment_threatening	bool	—	Harassment that threatens violence.
violence	bool	—	Non-graphic violence.

---

ModerationCategoryScores

Confidence scores for each moderation category.

Field	Type	Default	Description
sexual	f64	—	Sexual content score.
hate	f64	—	Hate speech score.
harassment	f64	—	Harassment score.
self_harm	f64	—	Self-harm content score.
sexual_minors	f64	—	Sexual content involving minors score.
hate_threatening	f64	—	Hate speech that threatens violence score.
violence_graphic	f64	—	Graphic violence score.
self_harm_intent	f64	—	Intent to self-harm score.
self_harm_instructions	f64	—	Instructions for self-harm score.
harassment_threatening	f64	—	Harassment that threatens violence score.
violence	f64	—	Non-graphic violence score.

---

ModerationRequest

Request to classify content for policy violations.

Field	Type	Default	Description
input	ModerationInput	ModerationInput::Single	Text or texts to check.
model	Option<String>	Default::default()	Model ID (e.g., "text-moderation-latest"). Optional; API uses default if unset.

---

ModerationResponse

Response from the moderation endpoint.

Field	Type	Default	Description
id	String	—	Unique identifier for this moderation request.
model	String	—	Model used for classification.
results	Vec<ModerationResult>	—	Results for each input string.

---

ModerationResult

A single moderation classification result.

Field	Type	Default	Description
flagged	bool	—	True if any category was flagged.
categories	ModerationCategories	—	Boolean flags for each moderation category.
category_scores	ModerationCategoryScores	—	Confidence scores for each category.

---

OcrImage

An image extracted from an OCR page.

Field	Type	Default	Description
id	String	—	Unique image identifier within the document.
image_base64	Option<String>	/* serde(default) */	Base64-encoded image data (if include_image_base64 was true).

---

OcrPage

A single page of OCR output.

Field	Type	Default	Description
index	u32	—	Page index (0-based).
markdown	String	—	Extracted page content as Markdown.
images	Option<Vec<OcrImage>>	/* serde(default) */	Embedded images extracted from the page (if include_image_base64 was true).
dimensions	Option<PageDimensions>	/* serde(default) */	Page dimensions in pixels, if available.

---

OcrRequest

An OCR request.

Field	Type	Default	Description
model	String	—	The model/provider to use (e.g. "mistral/mistral-ocr-latest").
document	OcrDocument	OcrDocument::Url	The document to process (URL or base64).
pages	Option<Vec<u32>>	vec!\[\]	Specific pages to process (1-indexed). None means all pages.
include_image_base64	Option<bool>	Default::default()	Whether to include base64-encoded images of each processed page.

---

OcrResponse

An OCR response.

Field	Type	Default	Description
pages	Vec<OcrPage>	—	Extracted pages in order.
model	String	—	Model/provider used for OCR.
usage	Option<Usage>	/* serde(default) */	Token usage, if reported by the provider.

---

PageDimensions

Page dimensions in pixels.

Field	Type	Default	Description
width	u32	—	Width in pixels.
height	u32	—	Height in pixels.

---

PromptTokensDetails

Breakdown of tokens used in the prompt portion of a request.

cached_tokens is included in Usage::prompt_tokens — it is not an additional charge on top of the prompt token count. When pricing supports a cache_read_input_token_cost, the cached portion is billed at the discounted rate and the remainder at the regular input rate.

Field	Type	Default	Description
cached_tokens	u64	—	Cached tokens present in the prompt. Defaults to 0 when absent.
audio_tokens	u64	—	Audio input tokens present in the prompt. Defaults to 0 when absent.

---

ProviderCapabilities

Static capability flags for a provider.

Each flag indicates whether the provider’s models generally support that feature. For providers that aggregate many underlying models (e.g. Bedrock, OpenRouter, vLLM) the flags reflect the superset of available model capabilities — a flag being true means at least one model supports the feature, not every model.

All flags default to false so that newly added providers are safe.

Access via the crate-level capabilities function:

Field	Type	Default	Description
vision	bool	—	The provider accepts image input in chat messages.
reasoning	bool	—	The provider supports extended-thinking / reasoning tokens.
structured_output	bool	—	The provider supports JSON-mode or response_format structured output.
function_calling	bool	—	The provider supports tool / function calling.
audio_in	bool	—	The provider accepts audio as input.
audio_out	bool	—	The provider can generate audio / TTS output.
video_in	bool	—	The provider accepts video as input.

---

ProviderConfig

Static configuration for a single provider entry in providers.json.

This struct deliberately does not include capability flags or streaming format, which are accessed via the capabilities function.

Field	Type	Default	Description
name	String	—	Provider identifier (matches the entry key in providers.json).
display_name	Option<String>	None	Human-readable provider name shown in UIs.
base_url	Option<String>	None	Base URL used as the default for this provider’s HTTP client.
auth	Option<AuthConfig>	None	Authentication scheme metadata (auth type + env var holding the key).
endpoints	Option<Vec<String>>	None	Supported endpoint kinds (e.g. chat, embeddings).
model_prefixes	Option<Vec<String>>	None	Model-name prefixes claimed by this provider (e.g. \["gpt-", "o1-"\]).
param_mappings	Option<HashMap<String, String>>	None	Parameter key renaming for this provider. Each entry maps an OpenAI-spec field name (e.g. "max_completion_tokens") to the name this provider expects (e.g. "max_tokens"). Applied automatically by ConfigDrivenProvider::transform_request.

---

RateLimitConfig

Configuration for per-model rate limits.

Field	Type	Default	Description
rpm	Option<u32>	None	Maximum requests per window. None means unlimited.
tpm	Option<u64>	None	Maximum tokens per window. None means unlimited.
window	std::time::Duration	60000ms	Fixed window duration (defaults to 60 s).

Methods

default()

Signature:

pub fn default() -> RateLimitConfig

Example:

let result = RateLimitConfig::default();

Returns: RateLimitConfig

---

RerankRequest

Request to rerank documents by relevance to a query.

Field	Type	Default	Description
model	String	—	Model ID (e.g., "cohere/rerank-english-v3.0").
query	String	—	The search query.
documents	Vec<RerankDocument>	vec!\[\]	Documents to rerank.
top_n	Option<u32>	Default::default()	Return only the top N results. Optional.
return_documents	Option<bool>	Default::default()	Include the document content in results. Defaults to false.

---

RerankResponse

Response from the rerank endpoint.

Field	Type	Default	Description
id	Option<String>	None	Unique identifier for this rerank request.
results	Vec<RerankResult>	—	Reranked documents in order of relevance.
meta	Option<serde_json::Value>	/* serde(default) */	Optional metadata about the reranking operation.

---

RerankResult

A single reranked document with its relevance score.

Field	Type	Default	Description
index	u32	—	Original document index in the input list.
relevance_score	f64	—	Relevance score in \[0, 1\]. Higher indicates more relevant.
document	Option<RerankResultDocument>	/* serde(default) */	Original document content (if return_documents was true).

---

RerankResultDocument

The text content of a reranked document, returned when return_documents is true.

Field	Type	Default	Description
text	String	—	Document text.

---

ResponseObject

Response from a structured response request.

Field	Type	Default	Description
id	String	—	Unique response ID.
object	String	—	Object type (e.g., "response").
created_at	u64	—	Unix timestamp of response creation.
model	String	—	Model used to generate the response.
status	String	—	Status (e.g., "succeeded", "failed").
output	Vec<ResponseOutputItem>	vec!\[\]	Output items from the response.
usage	Option<ResponseUsage>	Default::default()	Token usage.
error	Option<serde_json::Value>	Default::default()	Error details (if status is “failed”).

---

ResponseOutputItem

A single output item from the response.

Field	Type	Default	Description
item_type	String	—	Output type (e.g., "text", "object", "error").
content	serde_json::Value	—	Output content (flattened into the object).

---

ResponseTool

A tool available for the response request.

Field	Type	Default	Description
tool_type	String	—	Tool type (e.g., “extractor”, “search”).
config	serde_json::Value	—	Tool configuration (flattened into the object).

---

ResponseUsage

Token usage for a response.

Field	Type	Default	Description
input_tokens	u64	—	Input tokens used.
output_tokens	u64	—	Output tokens used.
total_tokens	u64	—	Total tokens used.

---

SearchRequest

A search request.

Field	Type	Default	Description
model	String	—	The model/provider to use (e.g. "brave/web-search", "tavily/search").
query	String	—	The search query string.
max_results	Option<u32>	Default::default()	Maximum number of results to return.
search_domain_filter	Option<Vec<String>>	vec!\[\]	Domain filter — restrict results to specific domains.
country	Option<String>	Default::default()	Country code for localized results (ISO 3166-1 alpha-2, e.g., "US", "FR").

---

SearchResponse

A search response.

Field	Type	Default	Description
results	Vec<SearchResult>	—	List of search results.
model	String	—	Model/provider that performed the search.

---

SearchResult

An individual search result.

Field	Type	Default	Description
title	String	—	Result title.
url	String	—	Result URL.
snippet	String	—	Text snippet or excerpt from the page.
date	Option<String>	/* serde(default) */	Publication or last-updated date, if available.

---

SingleflightResult

The value broadcast from a singleflight leader to all followers.

The error value is shared so every follower receives the same upstream failure without cloning the underlying error.

---

SpecificFunction

Name of the specific function to invoke.

Field	Type	Default	Description
name	String	—	Function name.

---

SpecificToolChoice

Directive to call a specific tool.

Field	Type	Default	Description
choice_type	ToolType	ToolType::Function	Tool type (always “function”).
function	SpecificFunction	—	The specific function to invoke.

---

StreamChoice

A streaming choice with incremental delta.

Field	Type	Default	Description
index	u32	—	Index of this choice in the choices array.
delta	StreamDelta	—	Incremental update to the message (content, tool calls, etc.).
finish_reason	Option<FinishReason>	Default::default()	Why the stream ended (present only in final chunk).

---

StreamDelta

Incremental delta in a stream chunk.

Field	Type	Default	Description
role	Option<String>	Default::default()	Role (typically present only in the first chunk).
content	Option<String>	Default::default()	Partial content chunk (e.g., a few words of the response).
tool_calls	Option<Vec<StreamToolCall>>	vec!\[\]	Partial tool calls being streamed.
function_call	Option<StreamFunctionCall>	Default::default()	Deprecated legacy function_call delta; retained for API compatibility.
refusal	Option<String>	Default::default()	Partial refusal message.
reasoning_content	Option<String>	Default::default()	Partial reasoning/thinking tokens (OpenAI-compatible extension used by DeepSeek R1, Qwen, etc.).

---

StreamFunctionCall

Partial function call details in a stream.

Field	Type	Default	Description
name	Option<String>	Default::default()	Function name (typically in the first chunk).
arguments	Option<String>	Default::default()	Partial JSON arguments chunk.

---

StreamOptions

Options for streaming responses.

Field	Type	Default	Description
include_usage	Option<bool>	Default::default()	If true, include token usage in the final stream chunk.

---

StreamToolCall

A streaming tool call being built incrementally.

Field	Type	Default	Description
index	u32	—	Index of this tool call in the tool_calls array.
id	Option<String>	Default::default()	Tool call ID (typically in the first chunk for this call).
call_type	Option<ToolType>	Default::default()	Tool type (typically “function”).
function	Option<StreamFunctionCall>	Default::default()	Partial function name and arguments.

---

SystemMessage

System message guiding model behavior for the entire conversation.

Field	Type	Default	Description
content	UserContent	UserContent::Text	Instructions or context that apply throughout the conversation. Accepts either a plain text string or an array of content parts, mirroring UserContent so that Message::system_with_parts works.
name	Option<String>	Default::default()	Optional name for the system message source.

---

ToolCall

A tool call the model wants to execute.

Field	Type	Default	Description
id	String	—	Unique ID for this call, used to reference in tool result messages.
call_type	ToolType	—	Tool type (always “function”).
function	FunctionCall	—	Function name and arguments.

---

ToolMessage

Tool execution result returned to the model.

Field	Type	Default	Description
content	UserContent	UserContent::Text	Result of the tool execution as plain text or an array of content parts (text, images, documents, audio), mirroring UserMessage::content. #\[serde(untagged)\] on UserContent means a bare JSON string still deserialises into Text, so tool results persisted before this field carried structured content continue to round-trip.
tool_call_id	String	—	ID of the tool call this result responds to.
name	Option<String>	Default::default()	Optional tool/function name.

---

TranscriptionResponse

Response from a transcription request.

Field	Type	Default	Description
text	String	—	The transcribed text.
language	Option<String>	Default::default()	Detected language (ISO-639-1 code).
duration	Option<f64>	Default::default()	Total audio duration in seconds.
segments	Option<Vec<TranscriptionSegment>>	vec!\[\]	Detailed segment-level transcription (if response_format is “verbose_json”).

---

TranscriptionSegment

A segment of transcribed audio with timing information.

Field	Type	Default	Description
id	u32	—	Segment index (0-based).
start	f64	—	Start time in seconds.
end	f64	—	End time in seconds.
text	String	—	Transcribed text for this segment.

---

Usage

Token-usage accounting returned by the provider on each completion / embedding call.

Field	Type	Default	Description
prompt_tokens	u64	—	Prompt tokens used. Defaults to 0 when absent (some providers omit this).
completion_tokens	u64	—	Completion tokens used. Defaults to 0 when absent (e.g. embedding responses).
total_tokens	u64	—	Total tokens used. Defaults to 0 when absent (some providers omit this).
prompt_tokens_details	Option<PromptTokensDetails>	Default::default()	Breakdown of tokens used in the prompt, including cached tokens served at the provider’s discounted cache-read rate. Absent when the provider does not return prompt-token details.

---

UserMessage

User message in the conversation.

Field	Type	Default	Description
content	UserContent	UserContent::Text	Message content as plain text or array of content parts (text, images, documents, audio).
name	Option<String>	Default::default()	Optional name for the user.

---

WaitForBatchConfig

Configuration for polling a batch until terminal status.

All time values are in seconds as f64 so the struct bridges across FFI boundaries without requiring a Duration shim.

Field	Type	Default	Description
initial_interval_secs	f64	5	Initial interval between polls, in seconds.
max_interval_secs	f64	60	Maximum interval between polls (backoff plateau), in seconds.
backoff_multiplier	f32	1.5	Exponential backoff multiplier (e.g., 1.5 increases delay by 50% each poll).
timeout_secs	Option<f64>	None	Optional timeout in seconds — polling fails if this duration is exceeded.

Methods

default()

Signature:

pub fn default() -> WaitForBatchConfig

Example:

let result = WaitForBatchConfig::default();

Returns: WaitForBatchConfig

---

Enums

Message

A chat message in a conversation.

Value	Description
System	System — Fields: 0: SystemMessage
User	User — Fields: 0: UserMessage
Assistant	Assistant — Fields: 0: AssistantMessage
Tool	Tool — Fields: 0: ToolMessage
Developer	Developer — Fields: 0: DeveloperMessage
Function	Deprecated legacy function-role message; retained for API compatibility. — Fields: 0: FunctionMessage

---

UserContent

User message content as either plain text or a list of multimodal parts.

Value	Description
Text	Plain text content. — Fields: 0: String
Parts	Array of content parts (text, images, documents, audio). — Fields: 0: Vec<ContentPart>

---

ContentPart

A single content part in a user message — text, image, document, or audio.

Value	Description
Text	Plain text. — Fields: text: String
ImageUrl	Image identified by URL (with optional detail level). — Fields: image_url: ImageUrl
Document	Document file (PDF, CSV, etc.) as base64 or URL. — Fields: document: DocumentContent
InputAudio	Audio input as base64. — Fields: input_audio: AudioContent

---

ImageDetail

Image detail level controlling token cost and processing.

Value	Description
Low	Low detail: scales image to 512x512, uses fewer tokens.
High	High detail: processes up to 2x2 grid of tiles, higher token cost.
Auto	Auto: model chooses low or high based on image dimensions.

---

AssistantContent

Content shape for assistant messages.

#[serde(untagged)] means providers returning a plain scalar string for the content field still deserialise correctly into AssistantContent::Text(_). Providers returning an array of typed parts (e.g. after an image-generation or audio-synthesis request) deserialise into AssistantContent::Parts(_).

Value	Description
Text	Plain text response (the common case for text-only models). — Fields: 0: String
Parts	Structured parts — text, refusals, output images, output audio. — Fields: 0: Vec<AssistantPart>

---

AssistantPart

One part of a structured assistant response.

#[serde(tag = "type", rename_all = "snake_case")] matches OpenAI’s parts-spec discriminator ("type": "text", "type": "output_image", …).

Value	Description
Text	A text segment of the response. — Fields: text: String
Refusal	A refusal — the model declined to respond. — Fields: refusal: String
OutputImage	An image produced by the model (e.g. gpt-image-1, Gemini Imagen). — Fields: image_url: ImageUrl
OutputAudio	Audio produced by the model (e.g. gpt-4o-audio-preview). — Fields: audio: AudioContent

---

ToolType

The type discriminator for tool/tool-call objects.

Per the OpenAI spec this is always "function". Using an enum enforces that constraint at the type level and rejects any other value on deserialization.

Value	Description
Function	Function

---

ToolChoice

Tool usage mode or a specific tool to call.

Value	Description
Mode	Predefined mode: auto, required, or none. — Fields: 0: ToolChoiceMode
Specific	Force a specific tool to be called. — Fields: 0: SpecificToolChoice

---

ToolChoiceMode

Tool choice mode.

Value	Description
Auto	Model may or may not call tools; default behavior.
Required	Model must call at least one tool.
None	Model must not call any tools.

---

ResponseFormat

Wire format for the chat completions response_format field.

Provider mapping

• OpenAI (and OpenAI-compatible providers): emitted verbatim as {"type": "json_schema", "json_schema": {...}} per the chat-completions spec.

• Gemini / Vertex AI: translated to generationConfig.responseMimeType = "application/json" and generationConfig.responseSchema = <schema>. The name, description, and strict fields are dropped — Gemini’s structured-output API does not consume them.

• Anthropic: no native JSON mode. A system instruction is prepended asking the model to respond with valid JSON. strict is advisory only; callers should still validate the returned JSON if the schema is load-bearing.

Value	Description
Text	Plain text output (default).
JsonObject	Output must be valid JSON object (no schema validation).
JsonSchema	Output must conform to the specified JSON schema. — Fields: json_schema: JsonSchemaFormat

---

StopSequence

Stop sequence(s) that cause the model to stop generating.

Value	Description
Single	Single stop sequence. — Fields: 0: String
Multiple	Multiple stop sequences. — Fields: 0: Vec<String>

---

Modality

Output modality requested from the model.

Passed as modalities: ["text", "audio"] (OpenAI) or translated to generationConfig.responseModalities (Gemini / Vertex AI).

Value	Description
Text	Text output (the default for all providers).
Audio	Audio / speech output.
Image	Image output (Gemini Imagen, gpt-image-1).

---

FinishReason

Why a choice stopped generating tokens.

Value	Description
Stop	Stop
Length	Length
ToolCalls	Tool calls
ContentFilter	Content filter
FunctionCall	Deprecated legacy finish reason; retained for API compatibility.
Other	Catch-all for unknown finish reasons returned by non-OpenAI providers. Note: this intentionally does not carry the original string (e.g. Other(String)). Using #\[serde(other)\] requires a unit variant, and switching to #\[serde(untagged)\] would change deserialization semantics for all variants. The original value can be recovered by inspecting the raw JSON if needed.

---

ReasoningEffort

Controls how much reasoning effort the model should use.

Value	Description
Low	Low
Medium	Medium
High	High
Minimal	Minimal
Max	Max

---

EmbeddingFormat

The format in which the embedding vectors are returned.

Value	Description
Float	32-bit floating-point numbers (default).
Base64	Base64-encoded string representation of the floats.

---

EmbeddingInput

Text or texts to embed.

Value	Description
Single	Single text string. — Fields: 0: String
Multiple	Multiple text strings (batch embedding). — Fields: 0: Vec<String>

---

ModerationInput

Input to the moderation endpoint — a single string or multiple strings.

Value	Description
Single	Single text string. — Fields: 0: String
Multiple	Multiple text strings (batch moderation). — Fields: 0: Vec<String>

---

RerankDocument

A document to be reranked — either a plain string or an object with a text field.

Value	Description
Text	Plain text document content. — Fields: 0: String
Object	Document with explicit text field (may include metadata). — Fields: text: String

---

OcrDocument

Document input for OCR — either a URL or inline base64 data.

Value	Description
Url	A publicly accessible document URL. — Fields: url: String
Base64	Inline base64-encoded document data. — Fields: data: String, media_type: String

---

FilePurpose

Purpose of an uploaded file.

Value	Description
Assistants	File for use with Assistants API.
Batch	File for batch processing.
FineTune	File for fine-tuning.
Vision	File for vision/image tasks.

---

BatchStatus

Status of a batch job.

Value	Description
Validating	Validating the input file.
Failed	Job failed.
InProgress	Job is running.
Finalizing	Finalizing results.
Completed	Job completed successfully.
Expired	Job expired before completion.
Cancelling	Job is being cancelled.
Cancelled	Job has been cancelled.

---

AuthHeaderFormat

How the API key is sent in the HTTP request.

Value	Description
Bearer	Bearer token: Authorization: Bearer <key>
ApiKey	Custom header: e.g., X-Api-Key: <key> — Fields: 0: String
None	No authentication required.

---

StreamFormat

The streaming wire format a provider uses for its response stream.

Most providers use standard Server-Sent Events (SSE). AWS Bedrock uses a proprietary binary EventStream framing.

Deserialized from the streaming_format JSON field via serde.

Value	Description
Sse	Standard Server-Sent Events (text/event-stream).
AwsEventStream	AWS EventStream binary framing (application/vnd.amazon.eventstream).

---

AuthType

Auth scheme used by a provider.

Value	Description
Bearer	Standard Authorization: Bearer <key> header.
ApiKey	x-api-key: <key> header (also handles "header" and "x-api-key" aliases).
None	No authentication header required.
Unknown	Unrecognised auth scheme — falls back to bearer.

---

Enforcement

How budget limits are enforced.

Value	Description
Hard	Reject requests that would exceed the budget with LiterLlmError::BudgetExceeded.
Soft	Allow requests through but emit a tracing::warn! when the budget is exceeded.

---

CacheBackend

Storage backend for the response cache.

Value	Description
Memory	In-memory LRU cache (default). No external dependencies.
OpenDal	OpenDAL-backed storage. Supports 40+ backends (S3, Redis, GCS, local FS, etc.). — Fields: scheme: String, config: HashMap<String, String>

---

CircuitState

Observable state of a circuit breaker.

Value	Description
Closed	Requests flow through normally.
Open	All requests are rejected; the circuit is waiting for the backoff to elapse.
HalfOpen	One probe request is allowed through to test service health.

---

HealthStatus

The result of a single health probe.

Value	Description
Healthy	The probe succeeded; the upstream is reachable.
Unhealthy	The probe failed; the upstream may be down.

---

RefreshOutcome

Result of a refresh_catalog call.

Value	Description
Disabled	config.enabled was false; no network, filesystem, or overlay activity occurred.
FromCache	The on-disk cache was fresh (age < ttl_seconds); the overlay was installed from the cached file without a network request.
Fetched	The catalog was fetched over the network, the cache file was (best-effort) refreshed, and the overlay was installed from the fetched catalog.

---

Errors

LiterLlmError

All errors that can occur when using liter-llm.

Variant	Description
Authentication	status preserves the exact HTTP status code received (401 or 403).
RateLimited	rate limited: {message}
BadRequest	status preserves the exact HTTP status code received (400, 405, 413, 422, …).
ContextWindowExceeded	context window exceeded: {message}
ContentPolicy	content policy violation: {message}
NotFound	not found: {message}
ServerError	status preserves the exact HTTP status code received (500, or other 5xx not covered by ServiceUnavailable).
ServiceUnavailable	status preserves the exact HTTP status code received (502, 503, or 504).
Timeout	request timeout
Streaming	A catch-all for errors that occur during streaming response processing. This variant covers multiple sub-conditions including UTF-8 decoding failures, CRC/checksum mismatches (AWS EventStream), JSON parse errors in individual SSE chunks, and buffer overflow conditions. The message field contains a human-readable description of the specific failure.
EndpointNotSupported	provider {provider} does not support {endpoint}
InvalidHeader	invalid header {name:?}: {reason}
Serialization	serialization error: {0}
BudgetExceeded	budget exceeded: {message}
HookRejected	hook rejected: {message}
InternalError	An internal logic error (e.g. unexpected Tower response variant). This should never surface in normal operation — if it does, it indicates a bug in the library.
OutboundForbidden	An outbound request was blocked by the active OutboundPolicy. Returned when register_custom_provider is called with a base_url that violates the policy (e.g. a private-range IP under DenyPrivate), or when the per-connection DNS resolver detects a forbidden address at connect time.
IdempotencyConflict	A different request body was submitted for an existing Idempotency-Key. Per the OpenAI Idempotency-Key convention, once a key is used with a particular request body, subsequent requests using the same key must carry an identical body. A body mismatch is a hard error (not retryable). HTTP equivalent: 409 Conflict.
IdempotencyInFlight	The same Idempotency-Key is already in-flight (another request with the same key is currently being processed). The caller should wait briefly and retry. The response is not yet available, and this request has been short-circuited to avoid running the operation twice. HTTP equivalent: 409 Conflict (retryable after a brief delay).

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CatalogRefreshError

Errors from refresh_catalog and install_catalog_overlay_from_str.

On every variant, the overlay registry is left untouched: a previously installed overlay (or the embedded catalog, if none was ever installed) remains active. This is the air-gap-safety contract — a failed refresh never degrades pricing/model-info availability.

Variant	Description
Disabled	Runtime catalog refresh was not enabled. refresh_catalog itself never returns this — it returns Ok(RefreshOutcome::Disabled) instead — but the variant is part of the public error surface for callers that want to treat “disabled” as a hard error.
InsecureUrl	source_url did not use the https scheme, or failed to parse as a URL at all. There is no host allowlist: the URL is user-configurable for self-hosted catalog mirrors, so only the scheme is enforced.
Fetch	The network fetch failed, timed out, or returned a non-success status.
Parse	The fetched or cached catalog JSON failed to parse.
Cache	A cache file read failed on an otherwise-fresh cache file. Cache write failures are best-effort and never surface as this error (see refresh_catalog).

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