Add api args and verbose parameters to Bedrock provider

[billsanto]

Added api_args and verbose parameters to the Bedrock provider. api_args is a list for parameters such as temperature, top_p, top_k, max_tokens, and stop_sequences. Added validation for each of these parameters. The verbose parameter adds useful information for developers and end users to inspect request and response headers and payloads. Updated the Roxygen documentation.

[atheriel]

It's definitely an oversight that chat_bedrock() does not yet have an api_args parameter. There's a lot going on here, though, some of which is discussed in #280 (a better parameters story) or #287 (debugging credentials, which is what I think you're mostly using verbose for -- emitting request details is already possible using httr2 features).

[hadley]

@billsanto thanks for working on this! As @atheriel says, I think this is probably a bit big, and anticipates some changes (like #280) that we'd rather tackle globally. Would you mind refocussing this PR on just enabling api_args? That should unblock you, without doing a bunch of work that we'll later have to roll back.

[billsanto]

Thanks--I figured the verbose option was more appropriate as a central feature, so yes I can refocus on the api_args for the PR. I really needed that functionality to figure out what was going on under the hood. Is there a way I get both headers and payloads using httr2 directly? This is what the verbose output currently looks like:

> devtools::load_all()
ℹ Loading ellmer
> 
> model <-"us.amazon.nova-lite-v1:0" #"us.meta.llama3-2-3b-instruct-v1:0" # "us.anthropic.claude-3-5-haiku-20241022-v1:0" #
> profile <- "default"
> api_args <- list(temperature = 0, max_tokens = 2000)#, top_k=2, top_p=.5, stop_sequences=list("STOP"))
> verbose <- TRUE
> 
> client <- chat_bedrock(
+   model = model,
+   profile = profile,
+   api_args = api_args,
+   verbose = verbose,
+ )
> resp <- client$chat("What is 1+1", echo=FALSE)

── AWS Credentials 
ℹ Profile: default; Key: --REDACTED--; Secret: T6****; Session: ; Region: us-east-2

── Request Body 
{
  "messages": [
    {
      "role": "user",
      "content": [
        {
          "text": "What is 1+1"
        }
      ]
    }
  ],
  "system": {},
  "toolConfig": {},
  "inferenceConfig": {
    "maxTokens": 2000,
    "temperature": 0
  }
} 
-> POST /model/us.amazon.nova-lite-v1:0/converse HTTP/2
-> Host: bedrock-runtime.us-east-2.amazonaws.com
-> User-Agent: httr2/1.1.0 r-curl/6.2.0 libcurl/8.11.1
-> Accept: */*
-> Accept-Encoding: deflate, gzip
-> x-amz-date: 20250203T151500Z
-> Authorization: AWS4-HMAC-SHA256 Credential=--REDACTED--/20250203/us-east-2/bedrock/aws4_request,SignedHeaders=host;x-amz-date;x-amz-security-token,Signature=4238b597731a55**6d8a6e885e7a
-> Content-Type: application/json
-> Content-Length: 150
-> 
<- HTTP/2 200 
<- date: Mon, 03 Feb 2025 15:15:02 GMT
<- content-type: application/json
<- content-length: 293
<- x-amzn-requestid: 63973db1-8600-4618-95f6-52f0d2d57f0c
<- 

── Response Body 
{
  "metrics": {
    "latencyMs": 475
  },
  "output": {
    "message": {
      "content": [
        {
          "text": "1 + 1 equals 2. This is a fundamental concept in arithmetic, where the sum of two ones results in the number two."
        }
      ],
      "role": "assistant"
    }
  },
  "stopReason": "end_turn",
  "usage": {
    "inputTokens": 6,
    "outputTokens": 29,
    "totalTokens": 35
  }
} 
> resp
[1] "1 + 1 equals 2. This is a fundamental concept in arithmetic, where the sum of two ones results in the number two."

> resp <- client$chat("What is 1+1", echo=TRUE)

── AWS Credentials 
ℹ Profile: default; Key: --REDACTED--; Secret: T6****; Session: ; Region: us-east-2

── Request Body 
{
  "messages": [
    {
      "role": "user",
      "content": [
        {
          "text": "What is 1+1"
        }
      ]
    },
    {
      "role": "assistant",
      "content": [
        {
          "text": "1 + 1 equals 2. This is a fundamental concept in arithmetic, where the sum of two ones results in the number two."
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "text": "What is 1+1"
        }
      ]
    }
  ],
  "system": {},
  "toolConfig": {},
  "inferenceConfig": {
    "maxTokens": 2000,
    "temperature": 0
  }
} 
-> POST /model/us.amazon.nova-lite-v1:0/converse-stream HTTP/2
-> Host: bedrock-runtime.us-east-2.amazonaws.com
-> User-Agent: httr2/1.1.0 r-curl/6.2.0 libcurl/8.11.1
-> Accept: */*
-> Accept-Encoding: deflate, gzip
-> x-amz-date: 20250203T153454Z
-> Authorization: AWS4-HMAC-SHA256 Credential=--REDACTED--/20250203/us-east-2/bedrock/aws4_request,SignedHeaders=host;x-amz-date;x-amz-security-token,Signature=6153f4782efb0dcb**383c4
-> Content-Type: application/json
-> Content-Length: 359
-> 
<- HTTP/2 200 
<- date: Mon, 03 Feb 2025 15:34:56 GMT
<- content-type: application/vnd.amazon.eventstream
<- x-amzn-requestid: 138bb922-d99e-4b8c-92ac-578e9e85fe07
<- 

── Response Stream 

── Response Chunk 
{
  "role": "assistant",
  "event_type": "messageStart"
} 

── Response Stream 

── Response Chunk 
{
  "contentBlockIndex": 0,
  "delta": {
    "text": "As"
  },
  "event_type": "contentBlockDelta"
} 

── Response Stream 

── Response Chunk 
{
  "contentBlockIndex": 0,
  "delta": {
    "text": " previously"
  },
  "event_type": "contentBlockDelta"
} 
As 
── Response Stream 

...

(Some manual redactions made for the post).

[hadley]

You can wrap any call with httrr2::with_vebosity(code, 2) in order to see the headers and bodies/streaming responses.