| name | firestore-costs-quotas |
| description | Use for Firestore data modeling, query design, listener usage, pagination, indexes, quotas and cost-aware architecture reviews. |
Purpose
Design Firestore access patterns that are secure, queryable and cost-aware before the app scales.
When to use
- Designing collections and documents.
- Optimizing Firestore queries or listeners.
- Estimating Firestore cost risk.
- Reviewing indexes, pagination or real-time updates.
Inputs to inspect
- Data model diagrams or repository code
- Collections, documents and subcollections
- Queries, listeners and pagination
- Indexes and Security Rules
- Offline persistence and sync behavior
Required workflow
- Start from user journeys and query requirements.
- Model documents around reads and authorization boundaries.
- Estimate read/write/listener behavior.
- Design pagination and indexes from real queries.
- Name cost, quota and security risks.
Rules
- Do not store images or base64 blobs in Firestore.
- Do not read full collections when pagination works.
- Do not attach broad global listeners by default.
- Avoid huge arrays for complex relationships.
- Design rules and indexes with the data model.
Related existing skills
Local skills to invoke
- firestore
- firebase-core
- android-architecture
- workmanager-background-sync
External companion skills to use when installed
Do not assume these companion skills are installed. Prefer the local skills above first, then consult Companion Skills for install and verification commands.
- firebase/agent-skills — use for deeper Firebase product, Firestore, Security Rules or emulator workflow guidance when installed.
Files commonly touched
- Repository Firestore code
firestore.rulesfirestore.indexes.json- DTO/domain models
- Sync managers
- Pagination UI state
Commands to validate
./gradlew test
firebase emulators:exec --only firestore "npm test"
Common mistakes to avoid
- Counting writes but ignoring listener re-reads.
- Using document IDs that leak sensitive relationships.
- Designing indexes after shipping slow queries.
- Ignoring offline cache invalidation.
Checklist
- Queries listed.
- Indexes considered.
- Pagination planned.
- Listener scope bounded.
- Cost and quota risks documented.
Example prompts
- Use $super-android-kotlin-firebase to review this Firestore model for cost risks.
- Use $super-android-kotlin-firebase to design paginated Firestore queries.
Expected response style
Respond with: brief diagnosis, change plan, affected files, code or diff summary, validation commands, tests added or recommended, risks, and next step. For review tasks, lead with findings ordered by severity.
References
- ../../docs/audits/FUENTES_LOCALES.md
- references/firestore-cost-model.md
- references/query-and-index-design.md
- references/listeners-and-pagination.md
- references/anti-patterns.md
- templates/firestore-data-model-review-template.md
- templates/pagination-query-template.md
- templates/cost-risk-report-template.md
