init xtdb -> datomic refactor

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+A REST API backend for managing code snippets, written in Clojure using XTDB for data storage. The API provides endpoints for creating, reading, editing, and deleting snippets, with support for tagging and slug-based lookup.
+
+**Related Projects:**
+- [Snippets CMS](https://git.travisshears.com/travisshears/snippets_cms) - TUI CMS and MCP server companion project
+
+## Development Commands
+
+### Run Development Server
+
+```sh
+clojure -M -m snippets.main
+```
+
+Starts the API server on the configured host/port (default: localhost:8080). The REPL can be used to develop with the server:
+
+```clojure
+; Start server in background from REPL:
+(def server (jetty/run-jetty #'app {:port 3000 :join? false}))
+; Stop server:
+(.stop server)
+```
+
+### Build Uberjar
+
+```sh
+clojure -T:build uber
+```
+
+Creates a standalone JAR file at `target/snippets-standalone.jar` that includes all dependencies.
+
+### REPL Commands
+
+Common REPL operations:
+
+```clojure
+; Pretty-print data structures
+(clojure.pprint/pprint {:name "Alice" :age 30})
+
+; Require a namespace (fresh import)
+(require 'clojure.string)
+(require '[clojure.string :as str])
+(require 'my.namespace :reload)
+
+; List namespace contents
+(dir clojure.string)
+
+; Switch namespaces
+(in-ns 'my.namespace)
+(in-ns 'user)
+```
+
+### Linting
+
+The project uses clj-kondo for static analysis. Configuration is in `.clj-kondo/config.edn`. Linting is integrated into most IDEs via LSP.
+
+## Code Architecture
+
+### Directory Structure
+
+- **src/snippets/infra/** - Infrastructure layer (HTTP API, database, configuration)
+  - `api.clj` - HTTP routing and handlers using reitit
+  - `db.clj` - XTDB queries and transactions
+  - `config.clj` - Configuration loading (config.edn + environment variables)
+- **src/snippets/use_cases/** - Business logic layer
+  - `view.clj` - Query/read operations, includes serialization for JSON output
+  - `create.clj` - Create snippets
+  - `edit.clj` - Patch snippets with validation
+  - `delete.clj` - Delete snippets
+- **test/** - Test suite
+
+### Architecture Pattern
+
+Clean separation between layers:
+
+1. **Infrastructure (infra/)**: Handles external concerns
+   - HTTP/REST via reitit + ring
+   - XTDB database client and queries
+   - Environment configuration
+
+2. **Use Cases**: Business logic implementing application features
+   - Each use case is a module with focused responsibility
+   - Calls infrastructure layer (infra.db, infra.config) as needed
+   - Performs serialization/transformation for API responses
+
+3. **Main Entry Point (main.clj)**: Minimal bootstrap that runs the API server
+
+### Data Model
+
+Snippets are XTDB documents with:
+- `xt/id` - UUID identifier (set by create use case)
+- `title` - Snippet title
+- `slug` - URL-friendly identifier for query lookups
+- `markdown` - Snippet content in markdown format
+- `tags` - Vector of strings for categorization
+- `pub-date` - Date object (serialized to ISO-8601 strings for API responses)
+
+### API Endpoints
+
+All routes under `/api`:
+
+- `GET /api/ping` - Health check
+- `GET /api/snippets` - List snippets (with optional `limit` and `skip` query params)
+- `GET /api/snippet?id=<id>` - Get snippet by UUID
+- `GET /api/snippet-by-slug?slug=<slug>` - Get snippet by slug
+- `POST /api/snippet` - Create snippet
+- `PATCH /api/snippet?id=<id>` - Edit snippet (patches are validated against schema)
+- `DELETE /api/snippet?id=<id>` - Delete snippet
+- `GET /api/tags` - List all tags with counts
+- `GET /api/tag?tag=<tag>` - Get snippets by tag
+
+### Key Dependencies
+
+- **reitit** (0.9.1) - HTTP routing and coercion
+- **ring** (1.13.0) - HTTP server (jetty adapter)
+- **XTDB** (2.0.0-beta9) - Temporal database
+- **malli** (0.18.0) - Schema validation and generation
+- **muuntaja** (0.6.11) - JSON/EDN encoding/decoding
+- **telemere** (1.0.0) - Structured logging
+- **environ** (1.2.0) - Environment variable loading
+
+### Configuration
+
+Configuration comes from `config.edn` with environment variable overrides:
+
+```edn
+{:jetty {:host "localhost" :port 8080}
+ :xtdb {:host "192.168.1.157" :port "5007" :user "xtdb" :dbname "xtdb"}}
+```
+
+Environment variables can override specific values:
+- `HOST` - Jetty host
+- `PORT` - Jetty port (parsed as integer)
+- `XTDB_HOST`, `XTDB_PORT`, `XTDB_USER`, `XTDB_DBNAME` - XTDB connection details
+
+See `infra/config.clj` for how overrides are applied.
+
+## Testing
+
+Run the test suite:
+
+```sh
+clojure -M:test:clojure.test/run
+```
+
+Or from REPL:
+
+```clojure
+(clojure.test/run-tests 'snippets-test)
+```
+
+The test namespace `snippets-test` includes:
+- Basic arithmetic tests
+- XTDB integration tests using test node
+- HTML rendering tests using rum
+
+## Deployment
+
+Docker image built and pushed to AWS ECR via `build.sh`:
+
+```sh
+./build.sh
+```
+
+Requires AWS CLI configured with `personal` profile and permission to push to ECR repository.
+
+## Notes
+
+- XTDB queries use XTQL (temporal query language)
+- Date serialization happens in `view.clj` - pub-date objects are converted to ISO-8601 strings for JSON responses
+- Patch validation is strict (`{:closed true}`) - only specific fields can be updated
+- String formatting in some XTQL queries uses `eval` and `read-string` for dynamic query construction
+- UUIDs used for snippet IDs; generated client-side on creation