Added offline token cost estimation with hard-isolated execution path

[saksham-jain177]

Implements --estimate-cost to provide an offline, pre-flight estimate of token usage and cost.

• Estimation runs in a fully isolated path before any provider initialization or network activity
• Token counting is approximate and provider-agnostic, as specified in the issue
• Cost lookup is best-effort and defaults to unavailable for unknown models
• Includes unit tests for the estimator

Closes #57

[brammittendorff]

Thanks for the suggestion! litellm is great but it's a pretty heavy dependency just for pricing lookups - it pulls in a lot of LLM client code we don't need.

Found a lighter option: genai-prices from Pydantic. It's specifically built for pricing data only. Covers 1000+ models across 29 providers, handles tiered pricing (Gemini), off-peak rates (DeepSeek), etc. No client bloat.

https://github.com/pydantic/genai-prices

Or we could just vendor their slim JSON directly.

Either way, we should add a disclaimer to the CLI output warning users that cost estimates are approximate and may not reflect current pricing.

What do you think?

[saksham-jain177]

I see, that makes sense. genai-prices looks like a good fit and avoids pulling unnecessary client code
if you’re aligned, I can update the PR to use genai-prices (or the JSON) while adding a clear disclaimer that estimates are approximate

I kept pricing static initially to stay strictly within the original issue scope.

[brammittendorff]

I see, that makes sense. genai-prices looks like a good fit and avoids pulling unnecessary client code if you’re aligned, I can update the PR to use genai-prices (or the JSON) while adding a clear disclaimer that estimates are approximate

I kept pricing static initially to stay strictly within the original issue scope.

Sounds good, I’m aligned.
Let’s use genai-prices directly, it’s small and keeps pricing updates centralized.
A clear disclaimer that prices are estimates is required.

Thanks for the thoughtful work on this.

[saksham-jain177]

Updated the PR to use genai-prices for dynamic pricing and added a clear disclaimer that estimates are approximate
All changes stay strictly within the original scope and CI is clean could you give it a review when you get a chance ?

[brammittendorff]

Updated the PR to use genai-prices for dynamic pricing and added a clear disclaimer that estimates are approximate All changes stay strictly within the original scope and CI is clean could you give it a review when you get a chance ?

A bit late but will do!

[brammittendorff]

from put them in the top of the file "if you can" or else isort has no use in our pipelines.

[brammittendorff]

from put them in the top of the file "if you can" or else isort has no use in our pipelines.

There are still some imports still in the code instead of in the top of the file. @saksham-jain177

[saksham-jain177]

from put them in the top of the file "if you can" or else isort has no use in our pipelines.

There are still some imports still in the code instead of in the top of the file. @saksham-jain177

Hey @brammittendorff, moved the remaining imports to the top of cost_estimator.py as required
Can you give it a check ?

[brammittendorff]

from put them in the top of the file "if you can" or else isort has no use in our pipelines.

There are still some imports still in the code instead of in the top of the file. @saksham-jain177

Hey @brammittendorff, moved the remaining imports to the top of cost_estimator.py as required Can you give it a check ?

Will check

[brammittendorff]

LGTM;