[AZ-185][AZ-186] Batch 2

Made-with: Cursor

_docs/02_tasks/done/AZ-185_update_manager.md

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+# Update Manager
+
+**Task**: AZ-185_update_manager
+**Name**: Update Manager
+**Description**: Implement the loader's background update loop that checks for new versions and applies AI model and Docker image updates
+**Complexity**: 5 points
+**Dependencies**: AZ-183, AZ-184
+**Component**: Loader
+**Tracker**: AZ-185
+**Epic**: AZ-181
+
+## Problem
+
+Jetsons need to automatically discover and install new AI models and Docker images without manual intervention. The update loop must handle version detection, server communication, and applying different update types.
+
+## Outcome
+
+- Loader automatically checks for updates every 5 minutes
+- New AI models downloaded, decrypted, and placed in model directory
+- New Docker images loaded and services restarted with minimal downtime
+- Loader can update itself (self-update, applied last)
+
+## Scope
+
+### Included
+- Version collector: scan model directory for .trt files (extract date from filename), query docker images for azaion/* tags, cache results
+- Background loop (configurable interval, default 5 min): collect versions, call POST /get-update, trigger downloads
+- Apply AI model: move decrypted .trt to model directory (detection API scans and picks newest)
+- Apply Docker image: docker load -i, docker compose up -d {service}
+- Self-update: loader updates itself last via docker compose up -d loader
+- Integration with AZ-184 Resumable Download Manager for all downloads
+
+### Excluded
+- Server-side /get-update endpoint (AZ-183)
+- Download mechanics (AZ-184)
+- CI/CD publish pipeline (AZ-186)
+- Device provisioning (AZ-187)
+
+## Acceptance Criteria
+
+**AC-1: Version collector reads local state**
+Given AI model azaion-2026-03-10.trt in model directory and Docker image azaion/annotations:arm64_2026-03-01 loaded
+When version collector runs
+Then it reports [{resource_name: "detection_model", version: "2026-03-10"}, {resource_name: "annotations", version: "arm64_2026-03-01"}]
+
+**AC-2: Background loop polls on schedule**
+Given the loader is running with update interval set to 5 minutes
+When 5 minutes elapse
+Then POST /get-update is called with current versions
+
+**AC-3: AI model update applied**
+Given /get-update returns a new detection_model version
+When download and decryption complete
+Then new .trt file is in the model directory
+
+**AC-4: Docker image update applied**
+Given /get-update returns a new annotations version
+When download and decryption complete
+Then docker load succeeds and docker compose up -d annotations restarts the service
+
+**AC-5: Self-update applied last**
+Given /get-update returns updates for both annotations and loader
+When applying updates
+Then annotations is updated first, loader is updated last
+
+**AC-6: Cached versions refresh after changes**
+Given version collector cached its results
+When a new model file appears in the directory or docker load completes
+Then cache is invalidated and next collection reflects new state
+
+## Constraints
+
+- Docker socket must be mounted in the loader container (already the case)
+- docker compose file path must be configurable (env var)
+- Model directory path must be configurable (env var)
+- Self-update must be robust: state file on disk ensures in-progress updates survive container restart