# System Architecture

Hireme is designed as a single-binary, local-first web application. It combines a high-performance backend, an embedded database, background job processing, and a lightweight frontend into a cohesive, easy-to-deploy system.

## Components

### 1. Database Layer (`internal/db`)

- **Technology:** SQLite3 via `github.com/mattn/go-sqlite3`.
- **Mode:** WAL (Write-Ahead Logging) mode is enabled (`PRAGMA journal_mode=WAL;`) to support high concurrency between the HTTP server reads and background worker writes without "database is locked" errors.
- **Pattern:** Centralized query methods attached to a `DB` struct (`queries.go`).

### 2. Worker Pool & Task Queue (`internal/worker`, `internal/db/tasks.go`)

- **Technology:** Custom goroutine worker pool pulling from a `tasks` SQLite table.
- **Tasks:**
  - `DISCOVER`: Initiates crawling on a target (e.g., Google Jobs search URL).
  - `FETCH`: Fetches raw HTML for a specific job posting.
  - `PROCESS`: Parses raw HTML, applies rule-based filtering (keywords, scoring), and enqueues for analysis if qualified.
  - `ANALYZE`: Sends the parsed job to an LLM for final qualification scoring and tailoring tips.
- **Concurrency:** Managed via context cancellation and `atomic.Bool` flags for safe pausing and resuming.

### 3. Filters & Rules (`internal/filter`, `data/config/filters.yaml`)

- A pipeline pattern is used to quickly reject jobs before doing expensive LLM API calls.
- **Hard Keywords:** Immediate rejection if a keyword (e.g., "Clearance", "Staff") is found.
- **Scoring Weights:** Basic substring counting for required technologies (e.g., "Go", "Python"). If the raw score falls below a threshold, the job is rejected.

### 4. Crawlers (`pkg/crawler`)

- Currently implements Google Jobs (`pkg/crawler/google`).
- **Mechanism:** Parses embedded JSON (`AF_initDataCallback`) in the raw HTML response rather than fragile DOM traversal. This ensures stability against UI changes.

### 5. UI Layer (`internal/ui`)

- **Technology:** Standard Go HTTP server (`net/http`), Go Templates (`html/template`), HTMX, and Tailwind CSS.
- **Philosophy:** Server-Side Rendered (SSR) HTML fragments returned directly to HTMX for seamless, single-page application (SPA) like updates without heavy JS payloads.
- **Templates:** Statically compiled strings in `.go` files (`template_layout.go`, `template_jobs.go`) rather than external `.html` files to keep the binary fully self-contained.

### 6. Logging (`internal/logger`)

- **Technology:** `go.uber.org/zap` (Sugared Logger).
- **Pattern:** Structured logging using `w` methods (`Infow`, `Errorw`, `Debugw`) to allow for strongly-typed key-value pairs (`"component", "API"`) instead of string formatting.