Cost calculation of aisdk from @posthog/ai is not cache aware #3022
Description
Is your feature request related to a problem?
Cost calculation in sendEventToPosthog
Costs are calculated as inputCostUSD = inputCost * inputTokens and outputCostUSD = outputCost * outputTokens without subtracting cache
Example:
The displayed cost is $0.0875765
But it should be
prompt_total = 21561
output_total = 139
cache_read = 17399
cache_write = 4157
# pricing reference: https://models.dev/?search=claude-sonnet-4-5%4020250929
price_input_per_1m = 3.0
price_output_per_1m = 5.0
price_read_per_1m = 0.3
price_write_per_1m = 3.75
# Assumption: Prompt total includes cache read and write tokens.
# Remainder is charged at standard input price.
standard_input_tokens = prompt_total - (cache_read + cache_write)
cost_standard = (standard_input_tokens / 1_000_000) * price_input_per_1m
cost_read = (cache_read / 1_000_000) * price_read_per_1m
cost_write = (cache_write / 1_000_000) * price_write_per_1m
cost_output = (output_total / 1_000_000) * price_output_per_1m
total_cost = cost_standard + cost_read + cost_write + cost_output
print(f"{standard_input_tokens=}")
print(f"{cost_standard=}")
print(f"{cost_read=}")
print(f"{cost_write=}")
print(f"{cost_output=}")
print(f"{total_cost=}")standard_input_tokens=5
cost_standard=1.5000000000000002e-05
cost_read=0.0052197
cost_write=0.01558875
cost_output=0.000695
total_cost=0.02151845
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Describe alternatives you've considered
Related sub-libraries
- All of them
- posthog-js (web)
- posthog-js-lite (web lite)
- posthog-node
- posthog-react-native
- @posthog/react
- @posthog/ai
- @posthog/nextjs-config
- @posthog/nuxt
- @posthog/rollup-plugin
- @posthog/webpack-plugin