Knowledge Base

I need to initialize resources (database connection pool, Redis client, HTTP client) when my FastAPI app starts and clean them up when it shuts down. The old @app.on_event('startup...

I want to use FastAPI's dependency injection system cleanly across route handlers. I have database sessions, current user extraction from JWT, and Redis clients that need to be inj...

After handling an API request (e.g., creating a trace), I want to trigger background processing (generate embeddings, send a notification email) without blocking the response. I ne...

I need to manage configuration for a FastAPI app across local dev, CI, and production environments. I use environment variables and .env files. I want type-safe settings with valid...

I need to bulk insert thousands of rows into PostgreSQL using SQLAlchemy 2.0 async. I want to do it efficiently with a single query (not one INSERT per row) and get back the genera...

I'm getting 'MissingGreenlet' or 'greenlet_spawn has not been called' errors when accessing related objects on my SQLAlchemy models in an async context. I need to understand which ...

I need to version my FastAPI API (v1, v2 eventually) without breaking existing clients when I introduce breaking changes. I want to organize routes in separate router modules per v...

I need structured JSON logging in my FastAPI application. I want request IDs correlated across log lines, log levels configurable via env var, and logs formatted as JSON in product...

I need to run multiple async operations concurrently in Python and collect all their results. Some operations may fail and I want to handle errors per-task. I'm using Python 3.11+ ...

I need to write async pytest tests for my FastAPI application. I need a test database that's rolled back after each test (not truncated), and I need to override FastAPI's database ...

I want to measure API request duration and expose it as a Prometheus metric. I need middleware that times every request, records the route, method, and status code, and exposes a /...

I need to implement a paginated list endpoint in FastAPI. The endpoint accepts optional filters (status, tag name) and pagination parameters (page, page_size). I want to avoid N+1 ...

My API uses snake_case internally (Python convention) but the frontend expects camelCase JSON. I need Pydantic models that accept and output camelCase JSON while keeping snake_case...

I have a function that handles multiple edge cases and I want to test all of them without writing a separate test function per case. I want to use pytest's parametrize decorator to...

I need to rate limit my FastAPI API endpoints. I want different limits for read vs write operations (e.g., 60 reads/min, 20 writes/min per API key). The rate limiter must be atomic...

I have a background worker (not FastAPI) that processes traces in a loop. Each batch of traces needs its own database session. I need to avoid session reuse across batches, handle ...

My FastAPI application raises various exceptions in different layers (validation errors, database errors, business logic errors) and I want all errors to return the same JSON struc...

I need to make HTTP calls to external APIs from my FastAPI application. I want a shared client with connection pooling (not a new client per request), configurable timeouts, and pr...

I need to create an async context manager for managing resources that need cleanup (database connections, temp files, locks). I want to use it with both `async with` syntax and as ...

I have a SQLAlchemy ORM model with sensitive fields (api_key_hash, internal_flags) that I don't want to expose in API responses. I also want to add computed fields to the response ...

I need to enforce a composite unique constraint across multiple columns in SQLAlchemy (e.g., one vote per user per trace, unique domain reputation per user per tag). I also need a ...

I have a background worker that processes items concurrently, but I don't want to overwhelm the database or external API. I need to limit the number of concurrent coroutines proces...

I need to add a new column to an existing PostgreSQL table that already has data. The column has a default value. I want to avoid locking the table and need to understand the migra...

I need to push real-time updates to browser clients when traces are validated or new search results arrive. I want to use WebSockets with FastAPI, handle connection cleanup when cl...

I'm building a Python service and not sure whether to use Python dataclasses, Pydantic models, or attrs for different data structures. I need to understand the tradeoffs for API sc...

My application makes calls to the OpenAI API and other external services. I want to write unit tests that don't make real HTTP calls, can test different response scenarios (success...

I'm writing Python code with strict type checking (mypy) and need to properly annotate functions that work with generic types: functions returning different types based on input, T...

My API has endpoints that return large datasets (100k+ rows). Offset-based pagination becomes slow at high page numbers. I need to implement cursor-based pagination that's efficien...

I need to insert records but update them if they already exist (upsert). This is common for incrementing counters, updating reputation scores, or syncing external data. I need the ...

I want to customize FastAPI's automatically generated OpenAPI documentation: add authentication scheme to Swagger UI, add custom descriptions and examples to request/response model...

I need to stream large query results from PostgreSQL without loading everything into memory. I want to use a Python async generator that yields rows in batches, and I want to suppo...

My pytest test suite is growing and I'm having trouble managing shared fixtures. I need to organize conftest.py files across a test hierarchy, understand fixture scoping, and share...

I need a /health endpoint for Docker healthchecks and load balancer probes. The endpoint should verify the database connection and Redis connection are alive, return structured hea...

I need to automatically track when rows are inserted or updated in my database tables for audit purposes. I want to log changes without modifying every query in my codebase.

I'm using Python Enum classes for status fields and vote types in my application. I need them to work correctly with SQLAlchemy (stored as strings in PostgreSQL, not as database en...

I need an endpoint that accepts file uploads (CSV, JSON, images). I need to validate file type, size limit the upload, and process the file asynchronously without blocking the serv...

I have a slow PostgreSQL query and I ran EXPLAIN ANALYZE. I need to understand how to read the output, identify why the query is slow (wrong index, bad join order, row estimate mis...

My FastAPI application has 20 workers and each worker has a SQLAlchemy connection pool of 5. This creates 100 connections to PostgreSQL, which is hitting the max_connections limit....

I have a PostgreSQL table where most queries filter on a specific condition (e.g., status='validated'). Creating a full index wastes space on non-matching rows and slows down write...

I have multiple API instances behind a load balancer and need to broadcast events (trace validated, new search result) to all instances. Redis pub/sub will fan out messages to all ...

My application has concurrent requests that update the same rows in different orders, causing deadlocks (ERROR: deadlock detected). I need to understand why deadlocks happen and ho...

My Docker image for a FastAPI app is 2GB and takes 5 minutes to build. I need a multi-stage Dockerfile producing a slim production image, using layer caching effectively to avoid r...

My Docker Compose setup has FastAPI, PostgreSQL, Redis, and a background worker. The services need to talk to each other. I am confused about when to use service names vs localhost...

I am deploying FastAPI with Nginx as a reverse proxy. I need SSL termination, proper forwarding headers (X-Forwarded-For), static file serving, and connection keepalive to the upst...

I need to manage environment variables for Docker Compose across multiple environments without committing secrets. I want .env file support with per-environment overrides.

I keep running into React hooks issues: state not updating immediately after setState, stale values in event handlers, and batching behavior I do not understand.

My React components have useEffect hooks causing memory leaks, firing too often from missing dependencies, or not re-running when I change a filter object. I need to understand cle...

I have API call state with loading, success, and error variants. Using optional fields allows impossible states. I want discriminated unions with full TypeScript narrowing.

I have full TypeScript types for my API responses and need derived types: making all fields optional for updates, picking a subset for list views, omitting sensitive fields, and re...

I need to share authenticated user state across many components without prop drilling. I want React Context with a pattern that avoids unnecessary re-renders when the setter is cal...

I am building with Next.js App Router and confused about when to use server vs client components, how to fetch data in server components, and how mutations work with server actions...

I need GitHub Actions to deploy to staging and production with secrets (API keys, deploy tokens) scoped per environment, with production requiring manual approval before deploy.

I want to deploy my FastAPI application to fly.io with a managed PostgreSQL database. I need fly.toml configuration, migration execution before deployment, and secure secret manage...

I need free HTTPS for my production server. I am using Nginx as a reverse proxy and need automatic certificate renewal with Let's Encrypt.

I have PostgreSQL with pgvector embeddings and a trust_score. I want semantic search that combines vector similarity with trust score for final ranking, without cutting off high-tr...

I need to rank traces by user votes. Simple upvote/total ratio fails for low-vote items (1/1 = 100% looks better than 95/100 = 95%). I need Wilson score lower bound for confidence-...

I need full-text search in PostgreSQL for finding traces by keywords. LIKE queries are too slow and do not support stemming. I want indexed text search with relevance ranking.

I have multiple API instances behind a load balancer and need to broadcast events (trace validated, vote cast) to all instances simultaneously. Redis pub/sub fans out to all subscr...

I have Redis and a Python background worker in Docker Compose. I need healthchecks so dependent services only start once Redis is ready, and I want the worker to report healthy onl...

I need to retry failing async operations (external API calls, database operations under transient load) with exponential backoff. I want a reusable decorator and to retry only on s...

I need to add a new NOT NULL column to an existing PostgreSQL table that has data. I need to avoid table locking in production and understand the correct staging for nullable -> ba...

I need fast async pytest tests for my FastAPI application using a real database. I want tests to roll back after each test rather than truncating tables, and override the FastAPI d...

I am building forms in React that have re-render performance issues from controlled inputs, complex validation, and async submission errors from the API. I want a clean performant ...

I want to stream OpenAI chat completion responses to users so tokens appear in real-time. I need to handle streaming in the backend (FastAPI) and forward it to the frontend using S...

I need to integrate Stripe Checkout for subscription payments. Users click a button, get redirected to Stripe's hosted checkout page, complete payment, and return to my app.

My React app re-renders excessively. I want practical guidance on when useMemo and useCallback actually help vs when they are premature optimization that adds overhead without bene...

I am migrating from Pydantic v1 to v2 and need custom validation: field-level validators that transform input (normalize strings, coerce types), cross-field validators comparing mu...

I want to measure API request duration and expose Prometheus metrics. I need middleware that times every request, records route and status code, and serves a /metrics endpoint for ...

I need a paginated list endpoint in FastAPI with optional filters (status, tag). I want efficient pagination with total count and no N+1 queries.

I need to understand best practices for async JavaScript/TypeScript: when to use Promise.all vs Promise.allSettled, how to handle errors in async patterns, and how to avoid common ...

My FastAPI application raises various exceptions in different layers and I want all errors to return a consistent JSON structure. I also want to map internal exceptions to appropri...

I have PostgreSQL queries that always filter on status='validated' and most queries only target this subset. A full index wastes space indexing pending rows I never query. I want p...

My API returns large datasets and offset-based pagination becomes slow at high page numbers. I need cursor-based pagination that stays O(log n) at any position in the dataset.

I need to decide when to use Python dataclasses, Pydantic models, TypedDict, or NamedTuple for different data structures in my application. Each has tradeoffs in validation, serial...

I need to bulk insert thousands of rows into PostgreSQL efficiently. Individual inserts in a loop are too slow. I want a single bulk INSERT and need the generated IDs back without ...

I need to run multiple async operations concurrently and collect all results. I want to handle cases where some may fail independently and need Python 3.11+ structured concurrency ...

I have a function handling many edge cases and want to test all of them without a separate test function per case. I want pytest parametrize with multiple inputs and expected outpu...

I need to version my FastAPI API (v1, v2 eventually) without breaking existing clients. I want routes organized in separate modules per version with versioned URL prefixes and shar...

I keep getting MissingGreenlet errors or N+1 queries when accessing related objects on SQLAlchemy models in an async context. I need to understand which loading strategies work wit...

My React app has a large JavaScript bundle. I want to split the code so users only download JS for the current page using React.lazy for component-level code splitting.

I need to push real-time updates (trace validated, vote cast) to browser clients. I want WebSockets with FastAPI, clean handling of client disconnections, and broadcast to all conn...

I need to automatically track when rows are inserted or updated in PostgreSQL for audit purposes. I want this without modifying every query in my codebase.

After handling an API request (creating a trace), I want to trigger background processing (generate embeddings) without blocking the response. The work should run after the respons...

I need to manage configuration for a FastAPI app across local dev, CI, and production environments using environment variables and .env files. I want type-safe settings with valida...

I have a SQLAlchemy ORM model with sensitive fields I don't want in API responses (api_key_hash, internal flags). I also want computed fields in the response. I need Pydantic v2 OR...

I am using Python Enum classes for status fields in my application and need them to work with SQLAlchemy (stored as strings), with Pydantic validation, and with JSON serialization ...

I need to unit test code that depends on external services (OpenAI, database, Redis). I want to mock these dependencies to test my business logic in isolation without real I/O.

I have concurrent reads and writes and am seeing unexpected behavior: dirty reads, non-repeatable reads, or phantom rows. I need to understand PostgreSQL isolation levels and when ...

I have trace metadata that varies by domain (language version, framework name, OS). I don't want to add columns for every possible field. I need JSONB storage with indexing for spe...

I have expensive database queries for search results I want to cache in Redis. I need a clean cache-aside pattern that serializes Pydantic models, handles Redis unavailability grac...

I have a slow PostgreSQL query and ran EXPLAIN ANALYZE but don't know how to read the output. I need to identify why the query is slow (wrong index, bad join order, row estimate mi...

I want to use a base docker-compose.yml for common configuration and override files for environment-specific settings (development with hot reload, production with resource limits,...

My Docker builds are slow because every code change invalidates the package installation layer. I need to structure my Dockerfile so that dependency installation is cached and only...

I need reusable data fetching hooks for my React application that handle loading, error, and success states, cache responses, revalidate on focus, and support optimistic updates.

I enabled TypeScript strict mode and now have many type errors. I need to understand what strict mode enables, how to fix common errors (possibly undefined, implicit any), and how ...

I want GitHub Actions to automatically create version tags and GitHub Releases when I push to main. I use conventional commits (feat:, fix:, chore:) and want semantic version bumps...

My GitHub Actions workflows take 10+ minutes mainly due to installing dependencies on every run. I need to cache dependencies, understand what to cache for Python and Node.js, and ...

My GitHub Actions workflows queue up multiple runs when I push rapidly. I want to cancel old runs when a new commit is pushed to the same branch, while still running all checks on ...

I am hitting OpenAI rate limits and getting RateLimitError exceptions. I need robust retry logic with exponential backoff specifically for OpenAI API calls, and I need to handle di...

I need to handle webhooks from multiple providers (Stripe, GitHub, custom services). I need a reusable pattern for signature verification, idempotent processing, and handling dupli...

My tests need realistic data (traces with tags, users with votes). Creating data manually in each test is verbose and fragile. I want factory fixtures that generate realistic test ...

I want to go beyond example-based tests to automatically discover edge cases in my code. I need property-based testing that generates diverse inputs and finds cases I would not thi...

I need consistent structured logging across my Python application. Logs need to be machine-parseable JSON in production but human-readable in development, with context (request_id,...

I need API key authentication for my FastAPI service. API keys must be stored securely (not plaintext), validated on every request, and I want to support multiple keys per user wit...

I need to stream large data exports from my FastAPI application. I want to generate NDJSON (newline-delimited JSON) as an async generator and stream it to the client without loadin...

I have expensive aggregation queries (contributor statistics, tag popularity, trust score distributions) that run on every page load. I want to precompute these and refresh them pe...

I have multiple API instances and need to ensure only one runs a specific operation at a time (e.g., leaderboard rebuild, scheduled job). I need a distributed mutex without adding ...

Alembic's autogenerate misses some schema changes: custom PostgreSQL types, check constraints, and index changes. I need to configure autogenerate to detect more changes and add ma...

I want TypeScript to check that objects match a type while preserving the most specific (narrowest) type for inference. I also want const objects with literal types not broadened t...

My modal component is inside a div with overflow:hidden or z-index stacking context that clips it. I need to render the modal at the document.body level while keeping it controlled...

I need to extend types from a third-party library (fastify, express, next.js) to add my own properties (current user, request context) without modifying the library's source code.

I need my GitHub Actions workflows to access AWS services (S3, ECR, ECS) without storing long-lived AWS credentials as GitHub secrets. I want keyless authentication using OIDC.

I have multiple FastAPI instances behind a load balancer. Simple in-memory rate limiting does not work because requests are distributed across instances. I need Redis-based rate li...

I want to let users log in with their GitHub account. I need to handle the OAuth2 flow: redirect to GitHub, receive the callback code, exchange for user info, and create/update a u...

I need end-to-end tests that verify my web application works from the user's perspective. I want to test user flows (search, vote, contribute) in a real browser using Playwright.

I want to measure test coverage in my Python project, enforce minimum coverage thresholds in CI, and track coverage changes over time. I use pytest and want coverage reported in th...

I have Python code using os.path and string concatenation for file paths that breaks on Windows. I need to use pathlib for cross-platform file operations that work on Linux, macOS,...

I need to build a command-line interface for my application with subcommands (import, export, stats), options with validation, and help text. I want it to be testable and support b...

I am using Python dataclasses for internal data objects. I need mutable default values (lists, dicts), computed fields that derive from other fields, and validation in __post_init_...

I have a many-to-many relationship between traces and tags. I need to create the join table correctly in SQLAlchemy, handle tag insertion with get-or-create semantics, and query tr...

I need my FastAPI routes to participate in database transactions where multiple operations must succeed or fail together. I want a dependency that manages the transaction lifecycle...

I have a complex UI component (a card with header, body, footer, and actions) that is hard to reuse because the structure is too rigid. I want a flexible composition pattern that l...

I am building a multi-tenant SaaS where each user should only see their own data. I want PostgreSQL row-level security (RLS) policies to enforce data isolation at the database leve...

Need to add full-text search to a PostgreSQL table. Users type natural-language queries like 'python async error handling' and expect relevant rows returned quickly without externa...

Need to enforce data isolation so each tenant can only see their own rows. Application-level filtering is error-prone — a missing WHERE clause leaks all data. Want database-enforce...

Storing metadata as JSONB columns for flexibility, but queries like `WHERE data->>'status' = 'active'` do full table scans. Need to index JSONB fields and write efficient queries.

Need to push real-time updates to connected clients when events occur (e.g., trace validated, vote received). Using Server-Sent Events (SSE) for the client side, need Redis pub/sub...

Need a real-time leaderboard that updates as scores change. Querying PostgreSQL for top-N with ORDER BY is expensive at scale. Need O(log N) updates and O(log N + K) range queries.

Managing different configurations for development, staging, and production in Docker Compose. Hardcoding environment variables in compose files leads to secrets in version control ...

Python Docker images are large (1GB+) because they include build tools, pip cache, and development packages. Need a lean production image while keeping a full dev environment. Usin...

FastAPI is running behind Nginx. Need rate limiting per client IP to prevent abuse, response caching for expensive endpoints, and gzip compression. Currently serving all traffic di...

Docker containers are ephemeral — data stored inside the container is lost on restart. Need to persist PostgreSQL data, handle Redis persistence, and share files between containers...

Component state has grown complex with multiple related fields that change together. useState is getting unwieldy with many separate setters. Need predictable state transitions and...

Duplicating data-fetching logic across components — each API call has its own loading/error/data state management. Need a generic, reusable data-fetching hook that works with any e...

Using Next.js App Router. Need to handle form submissions that mutate data on the server without building a separate API route. Want type-safe server-side form handling with optimi...

API calls return different shapes depending on success or failure. Using a generic `{ data: T | null, error: string | null }` pattern leads to redundant null checks everywhere and ...

Multiple deeply nested components need access to the same state (current user, theme, feature flags). Prop drilling has become unmanageable. Want to avoid Redux for a smaller app b...

Processing a large CSV or JSON file (hundreds of MB) by reading the entire file into memory causes out-of-memory errors. Need to process records one at a time as they're read from ...

Need to build a Docker image and push it to GitHub Container Registry (GHCR) on every push to main, with proper tagging (latest, sha, and version tags). Want to avoid rebuilding un...

Multiple repositories have duplicate CI/CD logic (lint, test, build). Updating the workflow in each repo separately is error-prone. Need a single source of truth for shared CI step...

CI pipeline runs tests automatically, but production deployment should require manual approval. Want automated staging deploy on merge to main, but production needs a human sign-of...

Using OpenAI chat completions but responses have high latency before any text appears. Need to stream the response token-by-token so users see text as it's generated, rather than w...

Implementing Stripe webhooks. Stripe sends events when payments succeed, subscriptions change, or invoices are created. Need to verify webhook signatures to prevent spoofed events ...

Need to send transactional emails (welcome emails, password resets, notifications) from a FastAPI application. Evaluating Resend as a simpler alternative to SendGrid/Mailgun with a...

Writing tests for a function that should behave differently based on many input combinations. Duplicating test functions for each case leads to hundreds of lines of copy-pasted cod...

Unit tests mock too much and don't catch integration bugs between routes, middleware, and database. Need integration tests that test the full HTTP stack (auth, rate limiting, actua...

Tests call external APIs (OpenAI, Stripe, GitHub). Real API calls make tests slow, expensive, and flaky. Need to intercept HTTP calls at the transport layer so the application code...

Async pytest fixtures are slow because they recreate expensive resources (database connections, HTTP clients) for each test. Need to understand fixture scoping in async contexts an...

Using Pydantic BaseModel for everything including internal data transfer objects (DTOs) that never touch the API boundary. Pydantic validation overhead is unnecessary for internal ...

Executing multiple independent async operations sequentially instead of concurrently. Using `asyncio.gather()` but need better error handling when one task fails — gather continues...

SQLAlchemy ORM queries are unexpectedly slow. EXPLAIN ANALYZE shows hundreds of small queries instead of a few efficient ones. The N+1 problem: loading a list of traces then access...

Expensive computations (tag normalization regex compilation, settings lookups, configuration parsing) run repeatedly with the same inputs. Need simple memoization without external ...

FastAPI services are tightly coupled to concrete implementations (PostgreSQL, Redis, specific email provider). Want to swap implementations for testing without monkey-patching or c...

Need to split a single `name` column into `first_name` and `last_name` columns. This requires a schema change (add columns, remove old) AND a data migration (populate new columns f...

Building code that needs to work with both asyncio and Trio event loops (or library code that shouldn't dictate the event loop). Also need nursery-style task cancellation that Task...

Application raises various exceptions (ValidationError, NotFound, PermissionDenied) but they all return inconsistent error responses. Clients can't reliably parse error details. Ne...

Getting errors like 'There is no current event loop' or 'coroutine was never awaited' in async Python code. Also confusion about when to use asyncio.run() vs await, and how to call...

Queries filter on multiple columns: `WHERE status = 'validated' AND trust_score > 0.5 ORDER BY created_at DESC`. Single-column indexes on each column aren't used effectively. Query...

Pydantic models need computed/derived fields that are calculated from other fields (e.g., full_name from first/last, formatted dates, masked API keys). Also need custom serializati...

Docker Compose healthchecks fail because the container doesn't have curl or wget installed in a slim image. Need a working healthcheck that works in minimal Alpine and Debian-slim ...

Manually managing server state with useState/useEffect is complex: tracking loading/error/stale states, deduplicating requests, invalidating cache after mutations. Looking for a de...

Using OpenAI chat completions to extract structured data from user input (classify intent, extract entities, fill forms). Parsing JSON from unstructured LLM output is fragile and r...

Query is slow but unsure why. Running EXPLAIN ANALYZE produces verbose output with nodes like 'Seq Scan', 'Hash Join', 'Bitmap Heap Scan' and numbers for cost, rows, and buffers. N...

Multiple workers process tasks concurrently and need to ensure only one worker handles a given resource at a time. Need a distributed lock that works across multiple API instances ...

Inserting thousands of rows one at a time with individual session.add() calls is too slow. Need bulk inserts that return the auto-generated IDs of inserted rows for downstream proc...

Docker Compose file has many services but not all are needed all the time. Dev needs API + DB, testing needs test DB too, production needs different services. Maintaining separate ...

Docker images need different configuration for different environments (staging vs production). Hardcoding config in the Dockerfile or passing everything at runtime isn't sufficient...

Need to protect certain routes in Next.js App Router — redirect unauthenticated users to /login, redirect logged-in users away from /login to dashboard. Doing this in each page com...

Defining configuration objects or lookup maps with TypeScript. Using `as const` loses type checking, using explicit type annotations loses inference of literal types. Need both: ty...

Bundle size is large because all components load upfront. Some pages are rarely visited. Need to split the bundle so users only download code for the routes they visit.

CI/CD pipeline needs secrets (API keys, deployment credentials) for different environments. Using repository-level secrets means production keys are accessible in all workflows inc...

Deploying a FastAPI application to Fly.io. Need to configure machine sizes, auto-scaling, health checks, persistent volumes for file storage, and secrets management for the deploym...

Calling the GitHub REST API to fetch repository data, user information, and pull request details. Hitting rate limits (60 req/hour unauthenticated, 5000/hour with token). Need to h...

Need to store and serve user-uploaded files (images, PDFs). Storing files in the filesystem doesn't work with multiple API instances or ephemeral containers. Need object storage th...

Integration tests need a real PostgreSQL database but spinning up a persistent test database causes state pollution between test runs, requires manual setup, and breaks in CI witho...

Working with union types and need TypeScript-style type guards in Python. After checking `isinstance(x, str)`, the type checker should know `x` is a `str` in that branch. Also need...

Test fixtures are duplicated across multiple test files. Each file has its own database setup, mock clients, and test data factories. Need a way to share fixtures across an entire ...

Resources like database connections, file handles, locks, and HTTP clients need cleanup even when exceptions occur. Using try/finally everywhere is verbose. Need the context manage...

Need real-time bidirectional communication between browser clients and the FastAPI server. REST/SSE only support server-to-client. Building a live collaboration feature where multi...

Using string literals for status values ('pending', 'validated', 'active') spread across the codebase. Typos cause silent bugs, IDEs can't autocomplete, and it's hard to find all p...

Using Python's standard logging module but log output is unstructured text that's hard to search in log aggregation tools (Datadog, Grafana Loki, CloudWatch). Need structured JSON ...

Storing OpenAI embedding vectors in PostgreSQL with pgvector. Need to query for the N most semantically similar traces given a query embedding. Query must filter by tags and status...

Need to track request latency, status code distribution, and active request counts across all endpoints. Want Prometheus metrics that work with Grafana dashboards, without duplicat...

Application needs configuration from multiple sources: environment variables override .env file, which overrides defaults. Also need nested settings objects (database config, Redis...

Deleting a parent record (User) should automatically delete child records (Traces, Votes). Without proper cascade configuration, SQLAlchemy either raises a foreign key constraint e...

Building a type-safe event system where events are named 'resource:action' (e.g., 'trace:created', 'user:updated'). Need TypeScript to enforce valid event names and infer payload t...

Background tasks are blocking the API event loop — image processing, email sending, report generation take seconds. FastAPI BackgroundTasks run in the same event loop. Need a prope...

FastAPI application runs behind Nginx as a reverse proxy. Regular HTTP requests work but WebSocket connections fail with 400 or 502 errors. Need Nginx configured to properly proxy ...

Building a complex form with nested fields, cross-field validation, and async validation (e.g., check if username is taken). Using controlled components with useState for each fiel...

Multiple service implementations (email: Resend, SendGrid; storage: S3, R2, local) need to be swappable. Using duck typing alone makes it unclear what methods a service must implem...

Blog posts and documentation pages are generated server-side on every request (SSR), causing slow TTFB. Content changes infrequently. Need static generation benefits (CDN caching, ...

FastAPI application with SQLAlchemy has database connection issues under load: timeouts, 'too many connections' PostgreSQL errors, and connection leaks. Default connection pool set...

Monorepo contains multiple services (api/, frontend/, mcp-server/). Every push runs all CI pipelines even when only one service changed. Need to run only the relevant pipelines bas...

FastAPI database dependency using SQLAlchemy async session. Need automatic transaction rollback when route handlers raise exceptions, and ensure sessions are always closed without ...

Calling external APIs (OpenAI, Stripe, GitHub) that occasionally return 429 (rate limit) or 503 (transient errors). Need automatic retry with exponential backoff, jitter to avoid t...

Alembic migration needs to modify an existing column (change type, add constraint) in a way that works on both PostgreSQL (production) and SQLite (tests/development). PostgreSQL su...

Need to run Alembic migrations that work on both PostgreSQL and SQLite. SQLite doesn't support ALTER TABLE for column renames or type changes, causing migration failures in test en...

Need to implement rate limiting for an API. Token bucket is too bursty, and fixed window has the boundary problem where a user can double their limit across two windows.

Building a typed API client where response types differ based on request parameters. Need type-safe response handling without runtime checks or type assertions.

CI pipeline uses matrix builds for multiple Python versions but stops all jobs when one fails. Need all matrix combinations to complete so developers see the full picture of compat...

MCP server (FastMCP 3.0.0) deployed to Railway crashes at runtime with `ModuleNotFoundError: No module named 'httpx'`, even though `httpx>=0.27` is listed under `[project].dependen...