feat(ui): show model usage price metrics

[w0wl0lxd]

Summary

• show effective input, output, cache-read, and cache-write prices per 1M tokens in /usage
• compute session estimates from each model attribution instead of repricing everything as the current model
• keep zero-priced providers unchanged and label coding-plan values as API-equivalent estimates
• preserve provider-qualified model specs for accurate cross-provider attribution

Research

• verified the existing provider catalog already carries input/output/cache rates and provider discovery can override them
• retained quota displays separately because coding/subscription plans do not report request-level dollar charges
• reused the existing token categories and cost arithmetic, including fast-mode cache multipliers

Validation

• cargo fmt --all
• cargo check --all
• cargo clippy --all --tests -- -D warnings
• cargo nextest run --workspace (5,234 passed, 4 skipped)

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: caa51252-164e-47b3-b70b-6e78869d7c93

📥 Commits

Reviewing files that changed from the base of the PR and between c718208 and cf1d987.

📒 Files selected for processing (1)

• n00n-ui/src/components/usage_modal.rs

📝 Walkthrough

Summary by CodeRabbit

• New Features

  • Usage details now show effective pricing, estimated costs, and savings for each model.
  • Session totals more accurately attribute usage across models.
  • Fast-tier pricing and cache rates are reflected in cost and savings calculations.
  • Pricing details include API-equivalent rate guidance.

• Bug Fixes

  • Zero-priced or unrecognized models remain visible without inflating cost or savings totals.
  • Completion events now include complete model specifications instead of only model IDs.

Walkthrough

The agent now reports full model specifications in completion events. Pricing calculations use centralized effective rates, including fast-tier cache rates. The usage modal attributes costs by model, displays effective pricing, and omits cost metrics for zero-priced models.

Changes

Model and Usage Reporting

Layer / File(s)	Summary
Agent event model specification n00n-agent/src/agent/compaction.rs, n00n-agent/src/agent/run.rs	Turn-complete events now report the full model specification for normal turns and compaction.
Effective pricing resolution n00n-providers/src/model.rs	ModelPricing::effective resolves standard or fast rates, derives cache rates, and supports centralized cost and savings calculations. Tests cover fast-rate resolution.
Usage pricing attribution and display n00n-ui/src/app/mod.rs, n00n-ui/src/components/usage_modal.rs, changelog.d/389.added.md	Usage costs use per-model pricing. Zero-priced models retain token usage but omit cost metrics. The modal displays effective rates and labels estimated costs. Tests cover pricing display and provider-qualified model resolution. The changelog records the pricing and attribution changes.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🟡 Moderate · up to c7182

The usage view can underreport mixed-session prices when a zero-priced model is present, while unresolved model parsing can omit attribution and provider-qualified models can appear under the same label. These bounded correctness and display issues should be fixed or explicitly accepted before merge.

Sequence Diagram(s)

sequenceDiagram
  participant UsageModal
  participant ModelPricing
  participant TokenUsage
  UsageModal->>ModelPricing: resolve pricing for each model
  ModelPricing-->>UsageModal: return effective rates
  UsageModal->>TokenUsage: calculate attributed cost and savings
  TokenUsage-->>UsageModal: return usage metrics
  UsageModal-->>UsageModal: render pricing lines and usage rows

Loading

Poem

A rabbit checks each model’s rate,
Fast cache totals calculate.
Full specifications appear,
Priced usage stays clear.
Zero-cost rows remain in view—
Hop, hop, the estimates are true!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: adding model usage price metrics to the UI.
Description check	✅ Passed	The description directly explains the pricing metrics, attribution changes, preserved behavior, research, and validation for this changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/usage-pricing

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[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[github-actions]

Criterion

Details

Benchmark suite	Current: cf1d987	Previous: 691fed3	Ratio
fib/jit_mlua_hook	6676050 ns/iter (± 93564)	6701811 ns/iter (± 35999)	1.00
fib/jit_watchdog	2283757 ns/iter (± 4831)	2224119 ns/iter (± 7964)	1.03
fib/jit_none	2275518 ns/iter (± 5992)	2224757 ns/iter (± 35783)	1.02
fib/interp_mlua_hook	8101782 ns/iter (± 85662)	8044330 ns/iter (± 279594)	1.01
fib/interp_watchdog	4300616 ns/iter (± 128693)	4276374 ns/iter (± 47848)	1.01
fib/interp_none	4281445 ns/iter (± 25713)	4307278 ns/iter (± 13919)	0.99
buffer_rw/jit_mlua_hook	582242 ns/iter (± 1650)	583948 ns/iter (± 1500)	1.00
buffer_rw/jit_watchdog	191360 ns/iter (± 365)	191598 ns/iter (± 379)	1.00
buffer_rw/jit_none	191348 ns/iter (± 5857)	191424 ns/iter (± 574)	1.00
buffer_rw/interp_mlua_hook	1037466 ns/iter (± 11334)	1074818 ns/iter (± 8303)	0.97
buffer_rw/interp_watchdog	583569 ns/iter (± 1098)	584134 ns/iter (± 14691)	1.00
buffer_rw/interp_none	582813 ns/iter (± 13743)	584099 ns/iter (± 1057)	1.00
splash_render_120x40	81172 ns/iter (± 356)	64280 ns/iter (± 6088)	1.26
splash_render_200x60	112086 ns/iter (± 4277)	192819 ns/iter (± 8009)	0.58

This comment was automatically generated by workflow using github-action-benchmark.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Criterion'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 2.

Benchmark suite	Current: 2f5dbe1	Previous: 45121b8	Ratio
buffer_rw/jit_mlua_hook	882685 ns/iter (± 48192)	430010 ns/iter (± 4387)	2.05

This comment was automatically generated by workflow using github-action-benchmark.

[codecov]

Codecov Report

❌ Patch coverage is 97.74648% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
n00n-ui/src/components/usage_modal.rs	98.04%	6 Missing ⚠️
n00n-agent/src/agent/run.rs	50.00%	1 Missing ⚠️
n00n-ui/src/app/mod.rs	83.33%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

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You have reached your Codex usage limits for security reviews. Please try again later.

[w0wl0lxd]

Applied the zero-priced-model finding in d68fbd7: attributed_costs now skips zero-priced models instead of discarding the whole fold, and returns None only when no priced model contributed. Added attributed_costs_skip_zero_priced_models_without_dropping_the_estimate covering the mixed priced/free session and the all-free session. 16/16 usage_modal tests pass.

[w0wl0lxd]

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[devin-ai-integration]

Devin Review found 1 new potential issue.

[linear-code]

N00N-402