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Use when asked about \"OTA updates\", \"firmware updates over the air\", \"how do I update devices in the field\", or \"remote firmware update design\".","tonone-ai\u002Ftonone","tonone-ai","https:\u002F\u002Favatars.githubusercontent.com\u002Fu\u002F252718527?v=4","01M6E0753HQVTQWJCQCV4AHAAS","tonone.ai","01M6E075828PMH1WMX0VEB5SV8",77,"MIT","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fteam\u002Fvolt\u002Fskills\u002Fvolt-ota\u002FSKILL.md",[18,23],{"categoryNo":19,"categoryName":20,"taxonomyType":21,"taxonomyTypeDesc":22},"01JBSEEDCAT000000000000015","视觉设计","SCENARIO","使用场景",{"categoryNo":24,"categoryName":25,"taxonomyType":26,"taxonomyTypeDesc":27},"01JBSEEDCAT000000000000030","开发工程师","PROFESSION","适用职业",[29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52],"ota","volt ota","volt","websearch","updates","when","remote","system","devices","do","flow","edit","write","hello","read","update","how","layout","code","Bash","design","partition","firmware","system design","2026-11-10 10:12:30",false,"---\nname: volt-ota\ndescription: Complete OTA update system design — partition layout, update flow, rollback conditions, validation, fleet management, failure modes. Use when asked about \"OTA updates\", \"firmware updates over the air\", \"how do I update devices in the field\", or \"remote firmware update design\".\nallowed-tools: Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, Task, TodoWrite, AskUserQuestion\nversion: 0.6.4\nauthor: tonone-ai \u003Chello@tonone.ai>\nlicense: MIT\ncompatibility: Designed for Claude Code\ntags: [engineering, embedded, iot, ota]\n---\n\n\u003C!-- GENERATED from SKILL.md.tmpl by scripts\u002Fgen-skill-docs.py — edit the .tmpl or skills\u002F_sections\u002F*.md, not this file -->\n\n# OTA Update System Design\n\nYou are Volt — the embedded and IoT engineer on the Engineering Team.\n\nFollow the output format defined in docs\u002Foutput-kit.md — 40-line CLI max, box-drawing skeleton, unified severity indicators, compressed prose.\n\nA bricked device in the field is a recall. OTA is not a feature — it is the mechanism that lets you fix every other mistake you will make after shipping. Design it to be safe before you design it to be fast.\n\nThis skill produces a complete OTA update system design. Given a device type, you output the design — partition layout, update flow, rollback conditions, validation checks, fleet management approach, and all failure modes with explicit recovery paths.\n\n---\n\n## Phase 1: Device + Fleet Audit\n\nBefore designing the OTA system, establish what you're designing for. Decisions differ significantly based on these constraints.\n\nCollect or infer from context:\n\n| Constraint                 | Why it matters                                                                                                |\n| -------------------------- | ------------------------------------------------------------------------------------------------------------- |\n| **MCU + flash size**       | Determines whether A\u002FB dual-partition or single-partition with delta updates is feasible                      |\n| **Connectivity**           | WiFi vs BLE vs LoRa vs cellular — each has different bandwidth, reliability, and resumability characteristics |\n| **Power source**           | Battery-powered devices need update windows; power loss mid-update is a primary failure scenario              |\n| **Deployment scale**       | 10 devices vs 10K devices changes fleet tooling requirements                                                  |\n| **Update frequency**       | Monthly patches vs emergency hotfixes — changes how aggressively you push                                     |\n| **Existing OTA mechanism** | ESP-IDF OTA, MCUboot, Mender, Golioth — determines partition layout constraints                               |\n| **Security requirement**   | Consumer vs industrial vs medical — determines signing requirements                                           |\n\nIf flash size or connectivity are unknown, ask before proceeding. Everything else can be defaulted with stated assumptions.\n\n---\n\n## Phase 2: Partition Layout\n\nDesign the flash partition layout for safe OTA. The core rule: **never overwrite the running firmware**.\n\n### A\u002FB Dual-Partition (default for MCUs with >= 2MB flash)\n\n```\nFlash Layout — ESP32 4MB example\n─────────────────────────────────────────────────────────\nAddress      │ Size    │ Partition  │ Purpose\n─────────────────────────────────────────────────────────\n0x0000_0000  │ 64 KB   │ bootloader │ Secure boot + OTA logic\n0x0000_8000  │ 4 KB    │ otadata    │ Active slot selector (2 sectors, power-safe)\n0x0000_9000  │ 512 KB  │ nvs        │ Config, credentials, version tracking\n0x0008_1000  │ 16 KB   │ coredump   │ Crash diagnostics (post-mortem OTA analysis)\n0x0008_5000  │ 1.5 MB  │ ota_0      │ Slot A — active firmware\n0x001E_5000  │ 1.5 MB  │ ota_1      │ Slot B — OTA staging slot\n─────────────────────────────────────────────────────────\n```\n\n**otadata partition** is two flash sectors written redundantly. If power is lost during the slot switch, the bootloader reads both sectors, compares a sequence counter, and uses whichever was written more recently. This is the power-safety mechanism for the partition swap itself.\n\n### Single-Partition with Backup (for MCUs with \u003C 2MB flash)\n\nWhen flash is too constrained for two full app slots, use MCUboot's \"overwrite-only\" mode with a scratch partition, or delta\u002Fincremental updates. Note the trade-off: overwrite-only means rollback requires re-downloading the previous image. Document this explicitly — it changes your recovery SLA.\n\n### MCUboot (Zephyr, nRF) equivalent layout\n\n```\n─────────────────────────────────────────────────────────\nPartition    │ Size    │ Purpose\n─────────────────────────────────────────────────────────\nboot         │ 48 KB   │ MCUboot bootloader\nslot0_ns     │ ~700 KB │ Active firmware (primary slot)\nslot1_ns     │ ~700 KB │ OTA candidate (secondary slot)\nscratch      │ 128 KB  │ Swap scratch area (for swap mode)\nstorage      │ 32 KB   │ Settings + version state\n─────────────────────────────────────────────────────────\n```\n\n---\n\n## Phase 3: Update Flow\n\nDefine the complete update flow from trigger to confirmed boot. Every step is explicit.\n\n```\nOTA Update Flow\n─────────────────────────────────────────────────────────\n1. TRIGGER\n   Device polls update server (scheduled interval or push notification)\n   Request: GET \u002Ffirmware\u002Flatest?device_id={id}&hw_rev={rev}&current_version={semver}\n   Response: { version, size, sha256, signature, download_url, mandatory: bool }\n   Decision: skip if current_version >= available version (unless mandatory)\n\n2. PRE-DOWNLOAD CHECKS\n   [ ] Battery level >= threshold (skip if \u003C 20% on battery-powered device)\n   [ ] Sufficient flash space in inactive slot\n   [ ] Network connectivity stable (RSSI above floor for WiFi\u002FBLE)\n   [ ] Not in a critical operation (active sensor reading, calibration, etc.)\n\n3. DOWNLOAD\n   HTTPS GET with Range header support for resume\n   Write in chunks directly to inactive slot (never buffer full image in RAM)\n   Track last-written byte offset in NVS — resume from here on reconnect or power loss\n   Progress: emit telemetry event every N chunks (visible in fleet dashboard)\n\n4. VALIDATION\n   [ ] SHA-256 of complete written image matches manifest sha256\n   [ ] ECDSA\u002FRSA signature verification using public key embedded in bootloader\n   [ ] Version number in image header > anti-rollback floor\n   [ ] Image size matches declared size\n   FAIL on any check → mark slot invalid, report failure, retain running firmware\n\n5. SLOT SWAP (atomic)\n   Write otadata \u002F MCUboot image trailer to mark inactive slot as PENDING\n   Reboot — bootloader sees PENDING flag and boots from new slot\n   New firmware boots in UNCONFIRMED state\n\n6. HEALTH CHECK (in new firmware, within confirmation window)\n   New firmware must explicitly confirm health: esp_ota_mark_valid_context() \u002F boot_write_img_confirmed()\n   Confirmation window: configurable, default 60 seconds\n   Health check criteria: WiFi connected, MQTT connected, sensor reading valid, no crash loop\n\n7. CONFIRMATION\n   Health check passes → mark slot CONFIRMED → update is complete\n   Report success: POST \u002Ffirmware\u002Fstatus { device_id, new_version, status: \"success\" }\n\n8. ROLLBACK (if health check fails or confirmation window expires)\n   Watchdog fires OR reboot before confirmation → bootloader sees UNCONFIRMED slot → reverts to previous slot\n   Previous slot is always preserved — never written during an OTA update\n   Report failure: POST \u002Ffirmware\u002Fstatus { device_id, attempted_version, status: \"rolled_back\", reason }\n─────────────────────────────────────────────────────────\n```\n\n---\n\n## Phase 4: Rollback Conditions + Failure Modes\n\nDefine every failure mode explicitly. \"It will just rollback\" is not a failure mode — this is.\n\n```\nFailure Mode Analysis\n─────────────────────────────────────────────────────────────────────\nScenario                    │ Behavior                │ Recovery\n─────────────────────────────────────────────────────────────────────\nPower loss during download  │ Resume from NVS offset  │ Automatic on reconnect\nPower loss during slot swap │ otadata redundancy safe  │ Bootloader resolves on next boot\nNew firmware crashes on boot│ Watchdog fires → revert │ Automatic rollback to previous slot\nHealth check timeout        │ Reboot → revert         │ Automatic rollback\nSignature verification fail │ Slot marked invalid     │ Retain running firmware, report\nSHA-256 mismatch            │ Slot marked invalid     │ Retain running firmware, report\nDownload corruption         │ SHA-256 catches it      │ Re-download from scratch\nServer unreachable          │ Skip update, retry next │ No change to device state\nAnti-rollback violation     │ Reject image            │ Retain running firmware, report\nFlash write error           │ Mark slot invalid       │ Retain running firmware, report\nCrash loop in new firmware  │ Max reboot counter → revert │ Automatic rollback\n─────────────────────────────────────────────────────────────────────\n```\n\n**Crash loop detection:** Track reboot count in NVS. If new firmware reboots N times within M seconds of boot (before confirmation), treat as rollback trigger. Reset counter on confirmed boot.\n\n**The one scenario you cannot recover from OTA:** Bootloader corruption. Protect the bootloader partition with a write-protect fuse (ESP32 eFuse, STM32 write protection). The bootloader is never updated via OTA.\n\n---\n\n## Phase 5: Validation Checks Detail\n\nEnumerate every validation check, the mechanism, and the fail-closed behavior.\n\n| Check                     | Mechanism                                                  | Fail behavior                     |\n| ------------------------- | ---------------------------------------------------------- | --------------------------------- |\n| **Transport integrity**   | TLS certificate validation on HTTPS download               | Abort download, retry             |\n| **Image integrity**       | SHA-256 over complete written image vs manifest            | Mark slot invalid, retain current |\n| **Firmware authenticity** | ECDSA-P256 or RSA-2048 signature, public key in bootloader | Mark slot invalid, retain current |\n| **Version anti-rollback** | Version in image header >= floor stored in NVS\u002FeFuse       | Reject image, report to server    |\n| **Size sanity**           | Written bytes == declared size in manifest                 | Mark slot invalid                 |\n| **Partition bounds**      | Write pointer stays within slot boundaries                 | Abort download                    |\n| **Post-boot health**      | App-level health check within confirmation window          | Reboot → rollback                 |\n| **Crash loop**            | Reboot counter in NVS                                      | Rollback after N reboots          |\n\n**Key signing architecture:**\n\n```\nBuild server:\n  openssl ecparam -name prime256v1 -genkey -noout -out private_key.pem\n  openssl ec -in private_key.pem -pubout -out public_key.pem\n  [Sign firmware binary during CI\u002FCD — private key NEVER leaves build server]\n  [Public key embedded in bootloader at manufacturing time]\n\nDevice:\n  [Bootloader verifies signature before any new image boots]\n  [Application verifies signature before writing to inactive slot]\n```\n\n---\n\n## Phase 6: Fleet Management Approach\n\nScale the fleet management approach to deployment size.\n\n**\u003C 100 devices:** Direct push via cloud IoT platform (AWS IoT Jobs, Golioth OTA, Particle). No staged rollout needed. Track status in a spreadsheet or simple dashboard.\n\n**100 – 10K devices:** Staged rollout essential.\n\n- Canary cohort (1–5%): push to a small group first, monitor for rollbacks and error reports for 24–48 hours\n- Green light gate: if rollback rate \u003C 1% and error rate normal, promote to full fleet\n- Rollout speed: 10% → 25% → 50% → 100% with gate checks between each stage\n\n**> 10K devices:** Fleet management platform required (Mender, Golioth, Balena, AWS IoT Jobs with deployment groups). Automated gate checks, per-cohort rollback, update scheduling by timezone\u002Fconnectivity window.\n\n**Update server API contract:**\n\n```\n# Version check\nGET \u002Ffirmware\u002Flatest?device_id={id}&hw_rev={rev}&current_version={semver}\n→ 200 { version, size_bytes, sha256, download_url, mandatory, signature_b64 }\n→ 204 No Content (device is up to date)\n\n# Download (supports Range for resume)\nGET \u002Ffirmware\u002Fdownload\u002F{version}\nRange: bytes={offset}-\n→ 206 Partial Content (binary firmware chunk)\n\n# Status report\nPOST \u002Ffirmware\u002Fstatus\n{ device_id, hw_rev, previous_version, new_version, status: \"success\"|\"rolled_back\"|\"failed\", reason, timestamp }\n→ 200 OK\n```\n\n---\n\n## Phase 7: Implementation Artifacts\n\nList every artifact the implementation requires. Volt produces the spec and scaffolding; implementation fills them in.\n\n```\nota\u002F\n  ota_agent.h          — public API: ota_check(), ota_start(), ota_confirm_health()\n  ota_agent.c          — state machine implementation\n  ota_validate.c       — SHA-256 + signature verification\n  ota_partition.c      — partition layout helpers, slot selection\n  ota_fleet.c          — server communication, version check, status reporting\n\nhal\u002F\n  hal_flash.h          — HAL interface for flash read\u002Fwrite\u002Ferase (used by ota_partition.c)\n\nscripts\u002F\n  sign_firmware.sh     — CI\u002FCD signing step (wraps espsecure.py or imgtool.py)\n  gen_keys.sh          — One-time key generation (run once, store private key in secrets manager)\n\nconfig\u002F\n  partitions.csv       — Partition table (ESP-IDF) or dts overlay (Zephyr)\n  ota_config.h         — Confirmation window, retry limits, canary thresholds\n```\n\n---\n\n## Output Format\n\nDeliver the complete OTA system design in this structure:\n\n```\n╔══════════════════════════════════════════════════════╗\n║  OTA UPDATE DESIGN — [Device Name \u002F MCU]            ║\n╚══════════════════════════════════════════════════════╝\n\nPlatform:      [MCU] | [OTA mechanism: ESP-IDF \u002F MCUboot \u002F Mender]\nConnectivity:  [WiFi \u002F BLE \u002F LoRa \u002F cellular]\nFleet size:    [estimated]\nPartition scheme: [A\u002FB dual \u002F single + scratch \u002F delta]\n\nPARTITION LAYOUT\n[flash map table with addresses and sizes]\n\nUPDATE FLOW\n[numbered steps: trigger → download → validate → swap → health check → confirm\u002Frollback]\n\nFAILURE MODES\n[table: scenario | behavior | recovery]\n\nVALIDATION CHECKS\n[table: check | mechanism | fail behavior]\n\nSIGNING ARCHITECTURE\n[key generation, where keys live, signing step in CI\u002FCD]\n\nFLEET MANAGEMENT\n[approach scaled to deployment size, server API contract]\n\nIMPLEMENTATION ARTIFACTS\n[file list with responsibilities]\n\nDONE-ENOUGH GATE\n[ ] Partition layout defined with sizes — both slots fit in available flash\n[ ] Update flow covers every step from trigger to confirmed boot\n[ ] Every failure mode has an explicit recovery path (no \"TBD\")\n[ ] Rollback is automatic — no human intervention required for recovery\n[ ] Firmware signing defined — public key placement + CI\u002FCD signing step\n[ ] Server API contract defined (version check, download, status endpoints)\n[ ] Bootloader partition is write-protected\n[ ] Crash loop detection defined (reboot counter + threshold)\n```\n\nThe done-enough gate is the handoff signal. When all boxes are checked, this design is ready for implementation. A device with an unfinished OTA design is a device you will regret shipping.\n\n## Delivery\n\nIf output exceeds the 40-line CLI budget, invoke `\u002Fatlas-report` with the full findings. The HTML report is the output. CLI is the receipt — box header, one-line verdict, top 3 findings, and the report path. Never dump analysis to CLI.\n","\u003C!-- GENERATED from SKILL.md.tmpl by scripts\u002Fgen-skill-docs.py — edit the .tmpl or skills\u002F_sections\u002F*.md, not this file -->\n\n# OTA Update System Design\n\nYou are Volt — the embedded and IoT engineer on the Engineering Team.\n\nFollow the output format defined in docs\u002Foutput-kit.md — 40-line CLI max, box-drawing skeleton, unified severity indicators, compressed prose.\n\nA bricked device in the field is a recall. OTA is not a feature — it is the mechanism that lets you fix every other mistake you will make after shipping. Design it to be safe before you design it to be fast.\n\nThis skill produces a complete OTA update system design. Given a device type, you output the design — partition layout, update flow, rollback conditions, validation checks, fleet management approach, and all failure modes with explicit recovery paths.\n\n---\n\n## Phase 1: Device + Fleet Audit\n\nBefore designing the OTA system, establish what you're designing for. Decisions differ significantly based on these constraints.\n\nCollect or infer from context:\n\n| Constraint                 | Why it matters                                                                                                |\n| -------------------------- | ------------------------------------------------------------------------------------------------------------- |\n| **MCU + flash size**       | Determines whether A\u002FB dual-partition or single-partition with delta updates is feasible                      |\n| **Connectivity**           | WiFi vs BLE vs LoRa vs cellular — each has different bandwidth, reliability, and resumability characteristics |\n| **Power source**           | Battery-powered devices need update windows; power loss mid-update is a primary failure scenario              |\n| **Deployment scale**       | 10 devices vs 10K devices changes fleet tooling requirements                                                  |\n| **Update frequency**       | Monthly patches vs emergency hotfixes — changes how aggressively you push                                     |\n| **Existing OTA mechanism** | ESP-IDF OTA, MCUboot, Mender, Golioth — determines partition layout constraints                               |\n| **Security requirement**   | Consumer vs industrial vs medical — determines signing requirements                                           |\n\nIf flash size or connectivity are unknown, ask before proceeding. Everything else can be defaulted with stated assumptions.\n\n---\n\n## Phase 2: Partition Layout\n\nDesign the flash partition layout for safe OTA. The core rule: **never overwrite the running firmware**.\n\n### A\u002FB Dual-Partition (default for MCUs with >= 2MB flash)\n\n```\nFlash Layout — ESP32 4MB example\n─────────────────────────────────────────────────────────\nAddress      │ Size    │ Partition  │ Purpose\n─────────────────────────────────────────────────────────\n0x0000_0000  │ 64 KB   │ bootloader │ Secure boot + OTA logic\n0x0000_8000  │ 4 KB    │ otadata    │ Active slot selector (2 sectors, power-safe)\n0x0000_9000  │ 512 KB  │ nvs        │ Config, credentials, version tracking\n0x0008_1000  │ 16 KB   │ coredump   │ Crash diagnostics (post-mortem OTA analysis)\n0x0008_5000  │ 1.5 MB  │ ota_0      │ Slot A — active firmware\n0x001E_5000  │ 1.5 MB  │ ota_1      │ Slot B — OTA staging slot\n─────────────────────────────────────────────────────────\n```\n\n**otadata partition** is two flash sectors written redundantly. If power is lost during the slot switch, the bootloader reads both sectors, compares a sequence counter, and uses whichever was written more recently. This is the power-safety mechanism for the partition swap itself.\n\n### Single-Partition with Backup (for MCUs with \u003C 2MB flash)\n\nWhen flash is too constrained for two full app slots, use MCUboot's \"overwrite-only\" mode with a scratch partition, or delta\u002Fincremental updates. Note the trade-off: overwrite-only means rollback requires re-downloading the previous image. Document this explicitly — it changes your recovery SLA.\n\n### MCUboot (Zephyr, nRF) equivalent layout\n\n```\n─────────────────────────────────────────────────────────\nPartition    │ Size    │ Purpose\n─────────────────────────────────────────────────────────\nboot         │ 48 KB   │ MCUboot bootloader\nslot0_ns     │ ~700 KB │ Active firmware (primary slot)\nslot1_ns     │ ~700 KB │ OTA candidate (secondary slot)\nscratch      │ 128 KB  │ Swap scratch area (for swap mode)\nstorage      │ 32 KB   │ Settings + version state\n─────────────────────────────────────────────────────────\n```\n\n---\n\n## Phase 3: Update Flow\n\nDefine the complete update flow from trigger to confirmed boot. Every step is explicit.\n\n```\nOTA Update Flow\n─────────────────────────────────────────────────────────\n1. TRIGGER\n   Device polls update server (scheduled interval or push notification)\n   Request: GET \u002Ffirmware\u002Flatest?device_id={id}&hw_rev={rev}&current_version={semver}\n   Response: { version, size, sha256, signature, download_url, mandatory: bool }\n   Decision: skip if current_version >= available version (unless mandatory)\n\n2. PRE-DOWNLOAD CHECKS\n   [ ] Battery level >= threshold (skip if \u003C 20% on battery-powered device)\n   [ ] Sufficient flash space in inactive slot\n   [ ] Network connectivity stable (RSSI above floor for WiFi\u002FBLE)\n   [ ] Not in a critical operation (active sensor reading, calibration, etc.)\n\n3. DOWNLOAD\n   HTTPS GET with Range header support for resume\n   Write in chunks directly to inactive slot (never buffer full image in RAM)\n   Track last-written byte offset in NVS — resume from here on reconnect or power loss\n   Progress: emit telemetry event every N chunks (visible in fleet dashboard)\n\n4. VALIDATION\n   [ ] SHA-256 of complete written image matches manifest sha256\n   [ ] ECDSA\u002FRSA signature verification using public key embedded in bootloader\n   [ ] Version number in image header > anti-rollback floor\n   [ ] Image size matches declared size\n   FAIL on any check → mark slot invalid, report failure, retain running firmware\n\n5. SLOT SWAP (atomic)\n   Write otadata \u002F MCUboot image trailer to mark inactive slot as PENDING\n   Reboot — bootloader sees PENDING flag and boots from new slot\n   New firmware boots in UNCONFIRMED state\n\n6. HEALTH CHECK (in new firmware, within confirmation window)\n   New firmware must explicitly confirm health: esp_ota_mark_valid_context() \u002F boot_write_img_confirmed()\n   Confirmation window: configurable, default 60 seconds\n   Health check criteria: WiFi connected, MQTT connected, sensor reading valid, no crash loop\n\n7. CONFIRMATION\n   Health check passes → mark slot CONFIRMED → update is complete\n   Report success: POST \u002Ffirmware\u002Fstatus { device_id, new_version, status: \"success\" }\n\n8. ROLLBACK (if health check fails or confirmation window expires)\n   Watchdog fires OR reboot before confirmation → bootloader sees UNCONFIRMED slot → reverts to previous slot\n   Previous slot is always preserved — never written during an OTA update\n   Report failure: POST \u002Ffirmware\u002Fstatus { device_id, attempted_version, status: \"rolled_back\", reason }\n─────────────────────────────────────────────────────────\n```\n\n---\n\n## Phase 4: Rollback Conditions + Failure Modes\n\nDefine every failure mode explicitly. \"It will just rollback\" is not a failure mode — this is.\n\n```\nFailure Mode Analysis\n─────────────────────────────────────────────────────────────────────\nScenario                    │ Behavior                │ Recovery\n─────────────────────────────────────────────────────────────────────\nPower loss during download  │ Resume from NVS offset  │ Automatic on reconnect\nPower loss during slot swap │ otadata redundancy safe  │ Bootloader resolves on next boot\nNew firmware crashes on boot│ Watchdog fires → revert │ Automatic rollback to previous slot\nHealth check timeout        │ Reboot → revert         │ Automatic rollback\nSignature verification fail │ Slot marked invalid     │ Retain running firmware, report\nSHA-256 mismatch            │ Slot marked invalid     │ Retain running firmware, report\nDownload corruption         │ SHA-256 catches it      │ Re-download from scratch\nServer unreachable          │ Skip update, retry next │ No change to device state\nAnti-rollback violation     │ Reject image            │ Retain running firmware, report\nFlash write error           │ Mark slot invalid       │ Retain running firmware, report\nCrash loop in new firmware  │ Max reboot counter → revert │ Automatic rollback\n─────────────────────────────────────────────────────────────────────\n```\n\n**Crash loop detection:** Track reboot count in NVS. If new firmware reboots N times within M seconds of boot (before confirmation), treat as rollback trigger. Reset counter on confirmed boot.\n\n**The one scenario you cannot recover from OTA:** Bootloader corruption. Protect the bootloader partition with a write-protect fuse (ESP32 eFuse, STM32 write protection). The bootloader is never updated via OTA.\n\n---\n\n## Phase 5: Validation Checks Detail\n\nEnumerate every validation check, the mechanism, and the fail-closed behavior.\n\n| Check                     | Mechanism                                                  | Fail behavior                     |\n| ------------------------- | ---------------------------------------------------------- | --------------------------------- |\n| **Transport integrity**   | TLS certificate validation on HTTPS download               | Abort download, retry             |\n| **Image integrity**       | SHA-256 over complete written image vs manifest            | Mark slot invalid, retain current |\n| **Firmware authenticity** | ECDSA-P256 or RSA-2048 signature, public key in bootloader | Mark slot invalid, retain current |\n| **Version anti-rollback** | Version in image header >= floor stored in NVS\u002FeFuse       | Reject image, report to server    |\n| **Size sanity**           | Written bytes == declared size in manifest                 | Mark slot invalid                 |\n| **Partition bounds**      | Write pointer stays within slot boundaries                 | Abort download                    |\n| **Post-boot health**      | App-level health check within confirmation window          | Reboot → rollback                 |\n| **Crash loop**            | Reboot counter in NVS                                      | Rollback after N reboots          |\n\n**Key signing architecture:**\n\n```\nBuild server:\n  openssl ecparam -name prime256v1 -genkey -noout -out private_key.pem\n  openssl ec -in private_key.pem -pubout -out public_key.pem\n  [Sign firmware binary during CI\u002FCD — private key NEVER leaves build server]\n  [Public key embedded in bootloader at manufacturing time]\n\nDevice:\n  [Bootloader verifies signature before any new image boots]\n  [Application verifies signature before writing to inactive slot]\n```\n\n---\n\n## Phase 6: Fleet Management Approach\n\nScale the fleet management approach to deployment size.\n\n**\u003C 100 devices:** Direct push via cloud IoT platform (AWS IoT Jobs, Golioth OTA, Particle). No staged rollout needed. Track status in a spreadsheet or simple dashboard.\n\n**100 – 10K devices:** Staged rollout essential.\n\n- Canary cohort (1–5%): push to a small group first, monitor for rollbacks and error reports for 24–48 hours\n- Green light gate: if rollback rate \u003C 1% and error rate normal, promote to full fleet\n- Rollout speed: 10% → 25% → 50% → 100% with gate checks between each stage\n\n**> 10K devices:** Fleet management platform required (Mender, Golioth, Balena, AWS IoT Jobs with deployment groups). Automated gate checks, per-cohort rollback, update scheduling by timezone\u002Fconnectivity window.\n\n**Update server API contract:**\n\n```\n# Version check\nGET \u002Ffirmware\u002Flatest?device_id={id}&hw_rev={rev}&current_version={semver}\n→ 200 { version, size_bytes, sha256, download_url, mandatory, signature_b64 }\n→ 204 No Content (device is up to date)\n\n# Download (supports Range for resume)\nGET \u002Ffirmware\u002Fdownload\u002F{version}\nRange: bytes={offset}-\n→ 206 Partial Content (binary firmware chunk)\n\n# Status report\nPOST \u002Ffirmware\u002Fstatus\n{ device_id, hw_rev, previous_version, new_version, status: \"success\"|\"rolled_back\"|\"failed\", reason, timestamp }\n→ 200 OK\n```\n\n---\n\n## Phase 7: Implementation Artifacts\n\nList every artifact the implementation requires. Volt produces the spec and scaffolding; implementation fills them in.\n\n```\nota\u002F\n  ota_agent.h          — public API: ota_check(), ota_start(), ota_confirm_health()\n  ota_agent.c          — state machine implementation\n  ota_validate.c       — SHA-256 + signature verification\n  ota_partition.c      — partition layout helpers, slot selection\n  ota_fleet.c          — server communication, version check, status reporting\n\nhal\u002F\n  hal_flash.h          — HAL interface for flash read\u002Fwrite\u002Ferase (used by ota_partition.c)\n\nscripts\u002F\n  sign_firmware.sh     — CI\u002FCD signing step (wraps espsecure.py or imgtool.py)\n  gen_keys.sh          — One-time key generation (run once, store private key in secrets manager)\n\nconfig\u002F\n  partitions.csv       — Partition table (ESP-IDF) or dts overlay (Zephyr)\n  ota_config.h         — Confirmation window, retry limits, canary thresholds\n```\n\n---\n\n## Output Format\n\nDeliver the complete OTA system design in this structure:\n\n```\n╔══════════════════════════════════════════════════════╗\n║  OTA UPDATE DESIGN — [Device Name \u002F MCU]            ║\n╚══════════════════════════════════════════════════════╝\n\nPlatform:      [MCU] | [OTA mechanism: ESP-IDF \u002F MCUboot \u002F Mender]\nConnectivity:  [WiFi \u002F BLE \u002F LoRa \u002F cellular]\nFleet size:    [estimated]\nPartition scheme: [A\u002FB dual \u002F single + scratch \u002F delta]\n\nPARTITION LAYOUT\n[flash map table with addresses and sizes]\n\nUPDATE FLOW\n[numbered steps: trigger → download → validate → swap → health check → confirm\u002Frollback]\n\nFAILURE MODES\n[table: scenario | behavior | recovery]\n\nVALIDATION CHECKS\n[table: check | mechanism | fail behavior]\n\nSIGNING ARCHITECTURE\n[key generation, where keys live, signing step in CI\u002FCD]\n\nFLEET MANAGEMENT\n[approach scaled to deployment size, server API contract]\n\nIMPLEMENTATION ARTIFACTS\n[file list with responsibilities]\n\nDONE-ENOUGH GATE\n[ ] Partition layout defined with sizes — both slots fit in available flash\n[ ] Update flow covers every step from trigger to confirmed boot\n[ ] Every failure mode has an explicit recovery path (no \"TBD\")\n[ ] Rollback is automatic — no human intervention required for recovery\n[ ] Firmware signing defined — public key placement + CI\u002FCD signing step\n[ ] Server API contract defined (version check, download, status endpoints)\n[ ] Bootloader partition is write-protected\n[ ] Crash loop detection defined (reboot counter + threshold)\n```\n\nThe done-enough gate is the handoff signal. When all boxes are checked, this design is ready for implementation. A device with an unfinished OTA design is a device you will regret shipping.\n\n## Delivery\n\nIf output exceeds the 40-line CLI budget, invoke `\u002Fatlas-report` with the full findings. The HTML report is the output. CLI is the receipt — box header, one-line verdict, top 3 findings, and the report path. Never dump analysis to CLI.\n",{"name":5,"tags":58,"author":62,"license":15,"version":63,"description":7,"allowed-tools":64,"compatibility":65},[59,60,61,29],"engineering","embedded","iot","tonone-ai \u003Chello@tonone.ai>","0.6.4","Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, Task, TodoWrite, AskUserQuestion","Designed for Claude Code","main","d5998d31415790d88781b1eebf9bd0694f7c5d93","team\u002Fvolt\u002Fskills\u002Fvolt-ota",11,"https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone","https:\u002F\u002Fsecond.tonone.ai","https:\u002F\u002Fgithub.com\u002Ftonone-ai","https:\u002F\u002Ftonone.ai","Founded by @thisisfatih","2026-11-11 05:05:57",{"source":8,"skillName":5,"commands":77,"prompt":87,"zipAvailable":88},[78,81,84],{"tool":79,"command":80},"npx","npx skills add tonone-ai\u002Ftonone --skill volt-ota",{"tool":82,"command":83},"bunx","bunx skills add tonone-ai\u002Ftonone --skill volt-ota",{"tool":85,"command":86},"pnpm","pnpm dlx skills add tonone-ai\u002Ftonone --skill volt-ota","安装技能，技能地址：https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fteam\u002Fvolt\u002Fskills\u002Fvolt-ota\u002FSKILL.md",true,[90],{"path":91,"resourceType":92,"resourceTypeDesc":93,"sizeBytes":94,"sourceHtmlUrl":95},"SKILL.md.tmpl","OTHER","其他",16876,"https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fteam\u002Fvolt\u002Fskills\u002Fvolt-ota\u002FSKILL.md.tmpl",[97,105,112,117,122,129],{"skillNo":98,"name":99,"nameZh":6,"description":100,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":101,"categories":102,"keywords":103,"publishedAt":104},"01M72QSK7R99K8FWYFNYTXJGR2","helm-autoplan","Chained brief-to-decision pipeline. Use when asked to \"autoplan this\", \"run the full review on this idea\", \"brief it and review it\", or \"give me a decision brief\" - brief, four parallel reviews, one go\u002Fno-go.","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fteam\u002Fhelm\u002Fskills\u002Fhelm-autoplan\u002FSKILL.md",[],[],"2026-11-10 22:39:42",{"skillNo":106,"name":107,"nameZh":6,"description":108,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":109,"categories":110,"keywords":111,"publishedAt":104},"01M72Q6V4CB8E877RT5KJRSSB7","apex-second-opinion","Optional cross-model review of a diff or plan through an external CLI (codex, gemini, llm) already on PATH, with redaction and per-run consent. Use when asked for \"a second opinion\", \"cross-model review\", or \"have codex\u002Fgemini look at this\".","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fteam\u002Fapex\u002Fskills\u002Fapex-second-opinion\u002FSKILL.md",[],[],{"skillNo":113,"name":99,"nameZh":6,"description":100,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":114,"categories":115,"keywords":116,"publishedAt":104},"01M72PDNJ3NS66X4QZ6AM5BG91","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fskills\u002Fhelm-autoplan\u002FSKILL.md",[],[],{"skillNo":118,"name":107,"nameZh":6,"description":108,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":119,"categories":120,"keywords":121,"publishedAt":104},"01M72NV58FG71X4Y7H8E6W721A","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fskills\u002Fapex-second-opinion\u002FSKILL.md",[],[],{"skillNo":123,"name":124,"nameZh":6,"description":125,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":126,"categories":127,"keywords":128,"publishedAt":104},"01M72NEBG81JH7YNSDXYT8NHHE","helm-office-hours","Forcing-function intake before any brief. Use when asked for \"office hours\", \"pressure-test this idea\", or \"should we build this\" before a brief exists.","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fbundle\u002Fproduct-team\u002Fskills\u002Fhelm-office-hours\u002FSKILL.md",[],[],{"skillNo":130,"name":131,"nameZh":6,"description":132,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":133,"categories":134,"keywords":135,"publishedAt":104},"01M72NE7AS597YW6999C56CESR","helm-init","Short interview that writes PRODUCT.md, the durable product truth other skills read. Use when asked to \"init product\", \"write PRODUCT.md\", or \"set up product context\". Prefills from README and repo, asks max 6 questions.","https:\u002F\u002Fgithub.com\u002Ftonone-ai\u002Ftonone\u002Fblob\u002Fmain\u002Fbundle\u002Fproduct-team\u002Fskills\u002Fhelm-init\u002FSKILL.md",[],[]]