🔧 Update Go module dependencies and modify NATS configuration to exclusively support JetStream mode. Upgrade go.uber.org/zap to version 1.27.1 and golang.org/x/crypto to version 0.45.0. Revise Makefile and documentation to reflect changes in NATS mode, ensuring consistent messaging behavior across development and production environments. Enhance README and configuration files to clarify JetStream usage and remove references to Core NATS mode.

docs/dev-guide.md

@@ -10,11 +10,7 @@ Spin up PostgreSQL/TimescaleDB and NATS JetStream in the background:
 docker compose -f docker-compose.dev.yml up -d postgres nats nats-box
 ```
 
-> **NATS Mode Selection:** The application supports two consumption modes:
-> - **Core NATS mode** (default for development): Simple pub/sub without persistence or retry mechanisms. Recommended for local development and testing where message loss is acceptable. Fast and lightweight.
-> - **JetStream mode**: Provides message persistence, ACK/NAK, automatic retries, and DLQ support. Recommended for production environments and integration testing.
->
-> Development mode defaults to `nats.mode = "core"` in `config.dev.toml`. To use JetStream in development, set `CAATSM_NATS_MODE=jetstream` or change the config file. **Note:** The publisher always targets JetStream for deduplicated fan-out, so if you use Core mode for consumption, ensure your publishers align with your messaging strategy. See the README.md "NATS Mode Selection" section for a detailed comparison.
+> **NATS Mode:** The application uses JetStream mode exclusively for message persistence, ACK/NAK, automatic retries, and DLQ support. This ensures consistent behavior across development, testing, and production environments.
 
 - `postgres` seeds the `aviation` schema using `internal/infra/postgres/telegrams.ddl` and exposes port `5432`.
 - `nats` enables JetStream with client port `4222` and monitoring/UI on `8222`.
@@ -55,7 +51,7 @@ docker compose -f docker-compose.dev.yml up -d postgres nats nats-box
 The `Taskfile.yml` includes helper targets that wrap the commands above:
 
 - `task up` – starts PostgreSQL, NATS (JetStream, toolbox, and Prometheus exporter), and the observability stack (OpenTelemetry Collector, Jaeger, Prometheus, Grafana) using Docker Compose.
-- `task dev-run` – ensures `task up` has run, exports the necessary `CAATSM_*` environment variables (defaults to `CAATSM_NATS_MODE=core` for development), and executes `go run ./cmd/main listen` with telemetry enabled.
+- `task dev-run` – ensures `task up` has run, exports the necessary `CAATSM_*` environment variables, and executes `go run ./cmd/main listen` with telemetry enabled.
 - `task down` – stops the entire stack and removes containers/volumes.
 
 Use these tasks if you prefer a one-command workflow instead of invoking `docker compose` and environment exports manually.
@@ -80,31 +76,17 @@ GO_ENV=dev go run ./cmd/seed-telegrams \
   --status random
 ```
 
-### Publishing to Core NATS
-
-For Core NATS mode, use standard publish:
-
-```bash
-# Publish to Core NATS (no persistence)
-GO_ENV=dev go run ./cmd/seed-telegrams \
-  --nats-url nats://127.0.0.1:4222 \
-  --subject telegram.serial \
-  --count 20 \
-  --category mixed \
-  --status random
-```
-
 ### Using Makefile/Taskfile Tasks
 
 For convenience, you can use the provided tasks:
 
 ```bash
-# Quick seed (10 messages, Core NATS)
+# Quick seed (10 messages, JetStream)
 make seed
 # or
 task seed
 
-# Continuous slow seeding (until Ctrl-C, JetStream by default)
+# Continuous slow seeding (until Ctrl-C, JetStream)
 make seed-slow
 # or
 task seed-slow
@@ -125,8 +107,6 @@ make seed-slow
 # Custom interval and category
 make seed-slow INTERVAL_MIN=5s INTERVAL_MAX=10s CATEGORY=DEP
 
-# Use Core NATS instead of JetStream
-make seed-slow USE_JS=false INTERVAL_MIN=1s INTERVAL_MAX=3s
 ```
 
 This is equivalent to running:
@@ -164,7 +144,7 @@ Setting `--count 0` makes it run indefinitely until interrupted.
 # View messages in JetStream stream
 docker compose exec nats-box nats stream view TELEGRAM
 
-# Subscribe to messages (Core NATS or JetStream)
+# Subscribe to messages (JetStream)
 docker compose exec nats-box nats sub 'telegram.>'
 
 # View consumer status and pending messages
@@ -184,22 +164,12 @@ The main processor keeps consuming `subscription.topic` (defaults to `telegram.>
 
 2. **Run the processor with telemetry enabled**
    ```bash
-   # Using Core NATS mode (default for development)
    CAATSM_TELEMETRY_ENABLED=true \
    CAATSM_TELEMETRY_ENDPOINT=localhost:4318 \
    CAATSM_TELEMETRY_INSECURE=true \
    GO_ENV=dev \
    CAATSM_POSTGRES_URL=postgres://caatsm:caatsm@localhost:5432/aviation?sslmode=disable \
    go run ./cmd/main listen
-   
-   # Or use JetStream mode for integration testing
-   CAATSM_TELEMETRY_ENABLED=true \
-   CAATSM_TELEMETRY_ENDPOINT=localhost:4318 \
-   CAATSM_TELEMETRY_INSECURE=true \
-   GO_ENV=dev \
-   CAATSM_NATS_MODE=jetstream \
-   CAATSM_POSTGRES_URL=postgres://caatsm:caatsm@localhost:5432/aviation?sslmode=disable \
-   go run ./cmd/main listen
    ```
    - The service name reported to Jaeger is `caatsm`.