Allow for prompt caching to work by using baibot_conversation_start_time_utc instead of baibot_now_utc

This patch introduces a new `baibot_conversation_start_time_utc`
variable which indicates the time the conversation got started.

Using `baibot_now_utc` is still possible, but given that the current
time is a moving target, its use is in conflict with prompt caching.

Because the new `baibot_conversation_start_time_utc` prompt variable
is a more reasonable default, we're now using it in all sample configs.

docs/configuration/text-generation.md

@@ -77,11 +77,14 @@ Prompts may contain the following **placeholder variables** which will be replac
 |---------------------------|-------------|---------|
 | `{{ baibot_name }}`       | Name of the bot as configured in the `user.name` field in the [Static configuration](./README.md#static-configuration) | `Baibot` |
 | `{{ baibot_model_id }}`   | Text-Generation model ID as configured in the [🤖 agent](../agents.md)'s configuration | `gpt-4o` |
-| `{{ baibot_now_utc }}`    | Current date and time in UTC | `2024-09-20 (Friday), 14:26:42 UTC` |
+| `{{ baibot_now_utc }}`    | Current date and time in UTC (⚠️ usage may break prompt caching - see below) | `2024-09-20 (Friday), 14:26:42 UTC` |
+| `{{ baibot_conversation_start_time_utc }}` | The date and time in UTC that the conversation started | `2024-09-20 (Friday), 14:26:42 UTC` |
+
+💡 `{{ baibot_now_utc }}` changes as time goes on, which prevents [prompt caching](https://platform.openai.com/docs/guides/prompt-caching) from working. It's better to use `{{ baibot_conversation_start_time_utc }}` in prompts, as its value doesn't change yet still orients the bot to the current date/time.
 
 Here's a prompt that combines some of the above variables:
 
-> You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+> You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
 
 
 ### 🌡️ Temperature Override

docs/sample-provider-configs/anthropic.yml

@@ -2,7 +2,7 @@ base_url: https://api.anthropic.com/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: claude-3-5-sonnet-20240620
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 8192
   max_context_tokens: 204800

docs/sample-provider-configs/groq.yml

@@ -2,7 +2,7 @@ base_url: https://api.groq.com/openai/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: llama3-70b-8192
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 4096
   max_context_tokens: 131072

docs/sample-provider-configs/localai.yml

@@ -2,7 +2,7 @@ base_url: http://my-localai-self-hosted-service:8080/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: gpt-4
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 4096
   max_context_tokens: 128000

docs/sample-provider-configs/mistral.yml

@@ -2,7 +2,7 @@ base_url: https://api.mistral.ai/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: mistral-large-latest
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 4096
   max_context_tokens: 128000

docs/sample-provider-configs/ollama.yml

@@ -2,7 +2,7 @@ base_url: http://my-ollama-self-hosted-service:11434/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: gemma2:2b
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 4096
   max_context_tokens: 128000

docs/sample-provider-configs/openai-compatible.yml

@@ -2,7 +2,7 @@ base_url: ''
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: some-model
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 4096
   max_context_tokens: 128000

docs/sample-provider-configs/openai.yml

@@ -2,7 +2,7 @@ base_url: https://api.openai.com/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: gpt-4o
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 16384
   max_context_tokens: 128000

docs/sample-provider-configs/openrouter.yml

@@ -2,7 +2,7 @@ base_url: https://openrouter.ai/api/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: mattshumer/reflection-70b:free
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 2048
   max_context_tokens: 8192

docs/sample-provider-configs/together-ai.yml

@@ -2,7 +2,7 @@ base_url: https://api.together.xyz/v1
 api_key: YOUR_API_KEY_HERE
 text_generation:
   model_id: meta-llama/Meta-Llama-3.1-405B-Instruct-Turbo
-  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time now is: {{ baibot_now_utc }}."
+  prompt: "You are a brief, but helpful bot called {{ baibot_name }} powered by the {{ baibot_model_id }} model. The date/time of this conversation's start is: {{ baibot_conversation_start_time_utc }}."
   temperature: 1.0
   max_response_tokens: 2048
   max_context_tokens: 8192