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docs(wiki): Lab-Mode page covering host + operator flows
Documents the host-initiated remote pair-flash session: trust model (opt-in, audit log, token rotation, no shell or arbitrary file surface, DPAPI vault for Wi-Fi credentials), how the host starts a session, how the operator drives it from another machine, the full typed command surface, server-side limits, and the troubleshooting table. Sidebar and home page link the new page.
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‎wiki/Home.md‎

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- [[Quick Start]] - install from a release zip and run the setup script.
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- [[Setup and Flashing]] - what the script does and how to recover a Pico.
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- [[Troubleshooting]] - what to run when setup or discovery fails.
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- [[Lab Mode]] - opt-in remote-flash session for collaborative testing.
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- [[Reporting-Bugs]] - how to make a bundle and what to include in an issue.
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- [[Build]] - build the release zip from source.
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- [[Protocol]] - short runtime and setup protocol reference.

‎wiki/Lab-Mode.md‎

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# Lab Mode
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Lab mode is an opt-in remote-flash session. The host starts a single
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subcommand, gets back a short URL, and shares it with the operator
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who is iterating on firmware from a different machine. The operator
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uploads UF2 builds, forces the Pico into BOOTSEL drive mode, flashes,
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runs the bridge's diagnostic ladder, and pulls the firmware diag ring
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-- all over a tunnel, with no shell or arbitrary file-read surface.
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This page is for hosts (people who have the Pico physically plugged
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in) and operators (developers who want remote access for testing).
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---
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## Trust model up front
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* The host runs `couchlink lab-mode` intentionally. The bridge is a
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normal foreground process; Ctrl+C ends the session and rotates the
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tokens so any URL that was shared stops working.
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* The accepted command surface is enumerated in code on both ends.
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The tunnel relay validates `kind` against an allowlist before
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queuing; the bridge validates again before dispatching. No
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arbitrary shell, no arbitrary file read, no process spawn.
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* Every command lands in
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`%LOCALAPPDATA%\ParsecCouchLink\data\logs\lab-mode.log` on the host
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as an audit trail.
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* Cleartext Wi-Fi credentials never traverse the tunnel. They live in
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a DPAPI-encrypted vault on the host, decrypted only when the
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operator triggers `wifi_apply_saved` and zeroized immediately after
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the CDC `SET_WIFI` call.
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---
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## Host: starting a session
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```powershell
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# One-time: stash your 2.4 GHz Wi-Fi credentials locally so you don't
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# have to type them every iteration. DPAPI keeps the blob bound to
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# your Windows login.
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couchlink save-wifi --ssid 'home2g' # prompts for the password
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# (or pass --password if you really want to)
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# (--clear deletes the saved vault)
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# Per session:
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couchlink lab-mode
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```
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Lab mode prints two lines and goes silent:
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```
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Lab session: https://couchlink.whyknot.dev/v/<token>
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Ctrl+C to end. Activity log: %LOCALAPPDATA%\ParsecCouchLink\data\logs\
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```
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Send the URL to the operator out-of-band (DM, email, signal -- it
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doubles as the auth, so treat it like a password). Press Ctrl+C any
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time to end. The tokens rotate whenever the bridge restarts.
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---
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## Operator: driving a session
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From a separate machine, in PowerShell:
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```powershell
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iwr https://couchlink.whyknot.dev/client.ps1 -UseBasicParsing | iex
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Set-CouchlinkSession 'https://couchlink.whyknot.dev/v/<token>'
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Get-CouchlinkInfo
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```
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`Get-CouchlinkInfo` lists `allowed_kinds` so you can see the live
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command set at any time.
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### Iteration loop
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```powershell
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Send-CouchlinkUf2 -Path .\couchlink-pico2w.uf2 # chunked + sha256
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Invoke-CouchlinkBootsel # CDC -> UDP -> picotool
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Wait-Couchlink -Ms 1500 # BOOTSEL drive mounts
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Invoke-CouchlinkFlash # flash the upload
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Wait-Couchlink -Ms 4000 # Pico reboots
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Get-CouchlinkPicoIdentity # CDC HELLO
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Invoke-CouchlinkWifiApplySaved # vault on the host
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Find-CouchlinkPico # UDP discovery
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Read-CouchlinkPicoLog | Out-Host # firmware diag ring
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```
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For a full forensic snapshot:
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```powershell
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Invoke-CouchlinkBundle -OutPath .\bundle.zip
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```
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For situational awareness:
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```powershell
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Watch-CouchlinkStream # live events
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Get-CouchlinkLabState # bridge state snapshot
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Get-CouchlinkStateJournal -Tail 50 # host's state-journal.log
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Get-CouchlinkBridgeLog -Tail 200 # today's bridge log
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Test-CouchlinkPing # relay + bridge RTT
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```
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---
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## Accepted commands
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The relay rejects any other `kind` with a 400 before queueing. The
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bridge enforces the same list as a second gate.
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| `kind` | Purpose |
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|-----------------------|--------------------------------------------------------------------|
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| `upload_uf2` | Upload a UF2 to the host's lab-mode slot, chunked. |
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| `flash` | Flash the most recently uploaded UF2 onto a mounted BOOTSEL drive. |
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| `force_bootsel` | Try CDC, then UDP, then `picotool reboot -u -f` to enter BOOTSEL. |
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| `doctor` | Run the bridge's 7-check diagnostic ladder. |
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| `bundle` | Build a support zip and stream it back via file_chunk / file_eof. |
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| `identify` | CDC HELLO. Returns fw triple + board + creds_present + wifi_joined.|
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| `discover` | UDP broadcast on 4242. Returns the first ACK. |
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| `ping` | Round-trip nonce echo for relay+bridge liveness. |
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| `state` | Bridge state snapshot (version, last Pico, vault presence). |
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| `pull_log` | UDP TYPE_GET_LOG against the latched Pico's diag ring. |
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| `read_state_journal` | Tail of `state-journal.log` (1..2000 lines). |
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| `read_bridge_log` | Tail of today's tracing log (1..2000 lines). |
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| `wifi_apply_saved` | Decrypt the host's DPAPI vault and CDC SET_WIFI in one shot. |
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| `wifi_clear` | CDC CLEAR_WIFI -- wipe Pico flash creds, re-enter setup mode. |
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| `sleep` | Bridge-side bounded sleep so scripts can sequence without timers. |
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---
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## Limits
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* 240 commands per 60 s per session at the relay (sliding window).
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* 2 MiB hard cap per command body at the relay.
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* 10 session mints per 60 s per source IP at the relay.
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* 24 h idle TTL on a session whose bridge has disconnected.
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* Wi-Fi vault: SSID up to 32 bytes, password up to 63 bytes (matches
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the firmware's flash_creds_t).
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* `read_state_journal` / `read_bridge_log`: 2000-line hard cap.
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* `sleep`: 60 000 ms hard cap.
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---
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## Troubleshooting
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| Symptom | Likely cause | Action |
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|-----------------------------------------------|-------------------------------------------------------------|------------------------------------------------------------------------------|
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| 404 on `Get-CouchlinkInfo` | View token expired (host restarted the bridge). | Ask the host for a fresh URL. |
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| `bridge_connected: False` persists | Bridge not running, or host network can't reach the relay. | Have the host restart `couchlink lab-mode`. Check their firewall / DNS. |
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| 400 with `kind not in lab-mode allowlist` | Unknown `kind` in the POST body. | Check the live list at `Get-CouchlinkInfo.allowed_kinds`. |
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| 413 on `Send-CouchlinkUf2` | Single chunk over 2 MiB. | Re-run with `-ChunkBytes 131072` (or smaller). |
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| 429 from the relay | More than 240 commands in 60 s on this session. | Back off; sequence with `Wait-Couchlink -Ms`. |
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| `bootsel_result.ok == false` for all methods | Pico USB is fully wedged. | Ask the host to physically power-cycle the Pico. |
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| `identify` reports `no setup-mode Pico found` | Pico is in run mode (XInput, not CDC). | Run `force_bootsel` then `flash`, or `wifi_clear` then power-cycle. |
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| `wifi_apply_saved` says `no saved Wi-Fi` | Host hasn't populated the vault yet. | Ask the host to run `couchlink save-wifi` on their own terminal. |

‎wiki/_Sidebar.md‎

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- [Quick Start](Quick-Start)
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- [Setup and Flashing](Setup-and-Flashing)
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- [Troubleshooting](Troubleshooting)
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- [Lab Mode](Lab-Mode)
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- [Build](Build)
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- [Protocol](Protocol)
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- [Changelog](Changelog)

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