feat(admin): add experiment-level cost exclusions

[charlesyhuang]

Extends cost-exclusion handling to experiments, allowing admins to register experiments (by name or id) whose trials are excluded from cost accounting, matching the existing LLM API key cost-exclusion feature. Implementation adds a new cost_excluded_experiments table and folds a not_excluded_experiment_filter into the shared cost-basis and quota-reservation predicates. The admin dashboard gains a Cost-excluded experiments card grouped with the existing Cost-excluded LLM keys card, backed by a mirrored /admin/cost-excluded-experiments API.

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Note

Medium Risk
Changes shared quota and cost-basis predicates used for billing enforcement; mistakes could mis-attribute spend, though behavior is covered by router and DB integration tests and mirrors the existing key-exclusion pattern.

Overview
Adds experiment-level cost exclusions alongside the existing LLM-key list: operators can register experiments (by id or unambiguous name) whose home trials are omitted from shared cost accounting.

Data & accounting: New cost_excluded_experiments table (soft-delete, one live row per experiment) and not_excluded_experiment_filter() wired into first_party_spend_filter() and quota inflight predicates so excluded spend does not appear on admin cost dashboards or count toward caps/reservations; removing an entry restores spend. Experiment pages still show raw trial cost.

API & UI: Operator-only GET/POST/DELETE /admin/cost-excluded-experiments, Next.js proxies, and a Cost-excluded experiments card on the admin Costs tab next to cost-excluded keys. Docs note this as a deployment-wide operator control.

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Project	Deployment	Actions	Updated (UTC)
oddish-app	Ready	Preview	Aug 8, 2026 11:55pm

[cursor]

Stale comment

Risk: high. Left a non-blocking comment — Cursor Bugbot reported an unresolved finding, and this PR changes cost/quota accounting with a migration, so it needs human review. Assigned reviewers stateofkate and RishiDesai.

  

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[cursor]

Risk: high. Left a non-blocking comment — Cursor Bugbot on the latest commit completed as skipped, and this PR changes cost/quota accounting with a migration, so it needs human review. Reviewers are already assigned.

  

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[github-actions]

Oddish preview

Commit: 85a81e8416310ce6f47ce39fadccc9385a9af5b5

Surface	Link	Target
Frontend	https://pr-1132.oddish.app	Vercel preview for 85a81e8
Backend	oddish-pr-1132	oddish-pr-1132
Database	project rshdtcxwbjyisteojife	project rshdtcxwbjyisteojife

Vercel deployment URL: https://oddish-odrwiupm5.oddish.app

Plan:

• Frontend deploy: true
• Backend deploy: false
• Migrations: false

This comment is updated by the PR Preview workflow.

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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[cursor]

Quota cancel skips experiment exclusion

High Severity

_active_trial_predicates still only applies not_excluded_llm_key_filter, so trials in cost-excluded experiments are cancelled when a quota fires even though their spend is omitted from settled sums and inflight reservation. That breaks parity with excluded LLM keys, which this path already preserves.

 

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