From d9894be7db07ddeea7b910643fa7299922c552ee Mon Sep 17 00:00:00 2001 From: Tobias Gesellchen Date: Sun, 10 May 2026 11:19:18 +0200 Subject: [PATCH] docs(analysis): add Telnet (port 17000) migration method analysis Documents the SSH-free third migration path on top of the device's diagnostic shell, synthesised from #221, #236, scheilch/opencloudtouch#167, deborahgu/soundcork#228, and deborahgu/soundcork#141. Captures the URL configuration command sequence, the dual persistence layers (`sys configuration` + `envswitch boseurls set`), the `/setMargeAccount` failure modes (404, hang, post-migration 502 on power_on) with their bounded fallbacks, port-17000 preflight requirements, and account-ID sourcing rules (reuse from `:8090/info`, pick from `DataStore.ListAccounts`, or 7-digit manual/randomized entry). Cross-links the new doc from DEVICE-REDIRECT-METHODS.md, marks the `/etc/hosts` method as deprecated, and fixes the existing margeServerUrl example to use our service's bare-URL convention with an explicit note for soundcork's `/marge` sub-path. Co-Authored-By: Claude Opus 4.7 (1M context) --- docs/SUMMARY.md | 1 + docs/analysis/DEVICE-REDIRECT-METHODS.md | 55 ++-- docs/analysis/TELNET-MIGRATION-METHOD.md | 343 +++++++++++++++++++++++ 3 files changed, 376 insertions(+), 23 deletions(-) create mode 100644 docs/analysis/TELNET-MIGRATION-METHOD.md diff --git a/docs/SUMMARY.md b/docs/SUMMARY.md index b65bab8..9336a04 100644 --- a/docs/SUMMARY.md +++ b/docs/SUMMARY.md @@ -61,6 +61,7 @@ * [Upstream URLs](analysis/UPSTREAM-URLS.md) * [Anonymization Summary](analysis/ANONYMIZATION-SUMMARY.md) * [Device Redirect Methods](analysis/DEVICE-REDIRECT-METHODS.md) +* [Telnet (Port 17000) Migration Method](analysis/TELNET-MIGRATION-METHOD.md) * [Wiki API Comparison](analysis/WIKI-COMPARISON.md) * [IoT Config Summary](analysis/IOT-CONFIG-SUMMARY.md) * [IoT Configuration Analysis](analysis/IOT-CONFIGURATION-ANALYSIS.md) diff --git a/docs/analysis/DEVICE-REDIRECT-METHODS.md b/docs/analysis/DEVICE-REDIRECT-METHODS.md index 9cbc868..39b6c07 100644 --- a/docs/analysis/DEVICE-REDIRECT-METHODS.md +++ b/docs/analysis/DEVICE-REDIRECT-METHODS.md @@ -2,6 +2,8 @@ To enable offline operation or use custom services like **SoundCork** or **ÜberBöse API**, SoundTouch devices must be redirected from Bose's official cloud endpoints to a local or custom server. This document outlines the three known methods to achieve this, gathered from community reverse-engineering efforts in the **SoundCork** and **ÜberBöse API** projects. +> A fourth, **SSH-free** path — driving the device's diagnostic shell on TCP port 17000 — is being added as a peer to the XML and DNS methods. See **[TELNET-MIGRATION-METHOD.md](TELNET-MIGRATION-METHOD.md)** for the use cases, community findings, and feasibility analysis. The `/etc/hosts` method documented below is now deprecated and will not be exposed in the web UI. + ## Overview of Redirection Targets SoundTouch devices primarily communicate with the following domains: @@ -32,19 +34,25 @@ The most robust and granular method involves modifying the device's private conf Requires SSH access to the device. ```xml - http://192.168.1.10:8000/marge + http://192.168.1.10:8000 http://192.168.1.10:8000 http://192.168.1.10:8000/updates/soundtouch http://192.168.1.10:8000/bmx/registry/v1/services ``` +> **Note on `margeServerUrl`** — `soundtouch-service` mounts the marge endpoints +> at the **root** of port 8000, so the URL has no `/marge` suffix. +> [`deborahgu/soundcork`](https://github.com/deborahgu/soundcork) routes marge +> under a `/marge` sub-path, so users redirecting to soundcork must append it +> (`http://192.168.1.10:8000/marge`). + ### Pros & Cons -| Pros | Cons | -| :--- | :--- | -| **Granular Control**: Redirect specific services while leaving others (e.g., updates) intact. | **Requires SSH**: Must have root/SSH access to the device. | -| **Persistent**: Survives software updates (usually). | **Syntax Sensitive**: Errors in XML can cause boot issues or service failures. | -| **Native**: Uses the device's built-in configuration mechanism. | | +| Pros | Cons | +|:----------------------------------------------------------------------------------------------|:-------------------------------------------------------------------------------| +| **Granular Control**: Redirect specific services while leaving others (e.g., updates) intact. | **Requires SSH**: Must have root/SSH access to the device. | +| **Persistent**: Survives software updates (usually). | **Syntax Sensitive**: Errors in XML can cause boot issues or service failures. | +| **Native**: Uses the device's built-in configuration mechanism. | | --- @@ -66,11 +74,11 @@ Requires SSH access. Add entries for the target domains: ``` ### Pros & Cons -| Pros | Cons | -| :--- | :--- | -| **Simple**: Easy to understand and implement. | **Requires SSH**: Must have root access. | +| Pros | Cons | +|:--------------------------------------------------------------------------------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| **Simple**: Easy to understand and implement. | **Requires SSH**: Must have root access. | | **Universal**: Affects all processes on the device attempting to reach those domains. | **HTTPS Issues**: Redirecting HTTPS domains to a local IP will cause SSL certificate errors unless the device is patched to skip verification or trust a custom CA. | -| | **Brittle**: Some firmware versions may overwrite `/etc/hosts` on reboot. | +| | **Brittle**: Some firmware versions may overwrite `/etc/hosts` on reboot. | --- @@ -104,12 +112,12 @@ sed "s#\^https:....bose.\+apigee..net..#http[aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 4. Restore execution permissions and reboot. ### Pros & Cons -| Pros | Cons | -| :--- | :--- | -| **Bypass Config**: Works even if the firmware ignores XML settings. | **High Risk**: Modifying binaries can lead to permanent bricks or boot loops. | +| Pros | Cons | +|:------------------------------------------------------------------------------------|:--------------------------------------------------------------------------------------| +| **Bypass Config**: Works even if the firmware ignores XML settings. | **High Risk**: Modifying binaries can lead to permanent bricks or boot loops. | | **Hardcoded Redirects**: Can catch URLs that aren't exposed in configuration files. | **Length Constraint**: Custom URLs must fit within the space of the original strings. | -| | **Firmware Specific**: Patches must be reapplied after every software update. | -| | **Complexity**: Requires understanding of binary structures and potential checksums. | +| | **Firmware Specific**: Patches must be reapplied after every software update. | +| | **Complexity**: Requires understanding of binary structures and potential checksums. | --- @@ -117,11 +125,11 @@ sed "s#\^https:....bose.\+apigee..net..#http[aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ### Summary Table -| Method | Primary Use Case | Ease | Safety | Persistence | Granularity | -| :--- | :--- | :---: | :---: | :---: | :---: | -| **XML Config** | Logical service redirection | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | -| **`/etc/hosts`** | Quick global DNS override | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐ | ⭐⭐ | -| **Binary Patch** | Bypassing hardcoded checks | ⭐ | ⭐ | ⭐ | ⭐⭐⭐ | +| Method | Primary Use Case | Ease | Safety | Persistence | Granularity | +|:-----------------|:----------------------------|:-----:|:------:|:-----------:|:-----------:| +| **XML Config** | Logical service redirection | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | +| **`/etc/hosts`** | Quick global DNS override | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐ | ⭐⭐ | +| **Binary Patch** | Bypassing hardcoded checks | ⭐ | ⭐ | ⭐ | ⭐⭐⭐ | --- @@ -176,9 +184,10 @@ As suggested by community members, you can configure the device to trust your ow - **Method B (Symlinks)**: Add the certificate to `/etc/ssl/certs/` and create a hash symlink using `c_rehash` (if available) or manual mapping. **Pros & Cons**: -| Pros | Cons | -| :--- | :--- | -| **Secure**: Maintains end-to-end encryption. | **Requires SSH**: Must have root access to modify the trust store. | + +| Pros | Cons | +|:-------------------------------------------------------|:-----------------------------------------------------------------------| +| **Secure**: Maintains end-to-end encryption. | **Requires SSH**: Must have root access to modify the trust store. | | **Clean**: No binary patching required for SSL bypass. | **Update Risk**: Firmware updates might overwrite the `ca-bundle.crt`. | ### Option 2: SSL Verification Bypass diff --git a/docs/analysis/TELNET-MIGRATION-METHOD.md b/docs/analysis/TELNET-MIGRATION-METHOD.md new file mode 100644 index 0000000..2484fdb --- /dev/null +++ b/docs/analysis/TELNET-MIGRATION-METHOD.md @@ -0,0 +1,343 @@ +# Telnet (Port 17000) Migration Method — Analysis + +This document captures the use cases, community findings, and feasibility analysis +for adding a **Telnet/port 17000** migration path to `soundtouch-service` as a +peer of the existing XML and DNS-based methods. The `/etc/hosts` method stays +deprecated and is intentionally kept off the visible UI options. + +> **Sources** — community discussion synthesised from +> [gesellix/Bose-SoundTouch#221](https://github.com/gesellix/Bose-SoundTouch/issues/221), +> [gesellix/Bose-SoundTouch#236](https://github.com/gesellix/Bose-SoundTouch/issues/236), +> [scheilch/opencloudtouch#167](https://github.com/scheilch/opencloudtouch/issues/167), +> [deborahgu/soundcork#228](https://github.com/deborahgu/soundcork/issues/228), +> [deborahgu/soundcork#141](https://github.com/deborahgu/soundcork/issues/141), +> the post-EOS walkthrough PDF in `docs/`, +> [Bose SoundTouch Telnet Probing thread](https://www.reddit.com/r/bose/comments/1o5zkym/soundtouch_telnet_probing/), +> and [flarn2006's blog post on hacking SoundTouch](https://flarn2006.blogspot.com/2014/09/hacking-bose-soundtouch-and-its-linux.html). + +--- + +## 1. Why a third method is needed + +The two currently shipped methods both have hard preconditions that block real +users: + +| Method | Preconditions | Failure modes seen in the wild | +|-----------------------------------------|--------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| **XML** (`SoundTouchSdkPrivateCfg.xml`) | SSH/root access — needs `remote_services` USB unlock first | Some firmware revisions (e.g. SA-5, ST520, latest ST Portable) refuse the USB unlock entirely; `remote_services on` was removed from the telnet command set in firmware 7.x and later. | +| **DNS** (`resolv.conf` priority hook) | SSH/root access; service must own port 53 on the LAN gateway | Won't fit users behind ISP routers they can't reconfigure; still requires the device to be SSH-reachable to write the hook. | + +The community has demonstrated a **third path that needs no SSH at all**: +the device's built-in **diagnostic Telnet shell on TCP port 17000** accepts +configuration commands that change exactly the same fields the XML method would. + +### 1.1 Confirmed user reports (firmware 27.0.6.46330.5043500 unless noted) + +| Reporter | Hardware | Outcome | +|--------------------|---------------------------|-------------------------------------------------------------------------------------------------------------| +| `foob61451` (#221) | ST 10, ST 20 (non-rooted) | All four URLs persisted via `sys configuration …`; `envswitch boseurls set …` survived `sys reboot`. | +| `bveenker` (#221) | Wave III | URLs accepted; presets work after pairing via `/setMargeAccount` (see §3). | +| `stephan48` (#221) | Wave IV | Telnet:1700 + USB stick `remote_services` did **not** work; **port 17000 telnet** worked for all four URLs. | +| `mcdona1d` (#141) | ST 20, ST 300 | Confirmed working with `sys configuration …` + `envswitch …` + `sys reboot`. | +| `TJGigs` (#228) | ST 20 ×2, ST 10 | Wraps telnet:17000 into an admin "Smart Inject" tool; uses `sys reboot` over telnet to nudge devices. | + +So the method is plausible across **at least ST 10/20/300 and Wave III/IV** on +the most common firmware that survived the EOS cut, **without the USB unlock +dance** that newer firmware refuses. + +--- + +## 2. The Telnet:17000 command set we rely on + +### 2.1 URL configuration (the migration payload) + +The sequence we send for `soundtouch-service` (community-validated in #221, #141): + +``` +sys configuration bmxRegistryUrl http://:8000/bmx/registry/v1/services +sys configuration statsServerUrl http://:8000 +sys configuration margeServerUrl http://:8000 +sys configuration swUpdateUrl http://:8000/updates/soundtouch +envswitch boseurls set http://:8000 http://:8000/updates/soundtouch +getpdo CurrentSystemConfiguration +sys reboot +``` + +Three important details from the discussion: + +1. **`sys configuration` alone is not enough.** `stephan48` reported that + without the `envswitch boseurls set …` line his typo in `bmxRegistryUrl` was + silently restored on reboot — i.e. there is a parallel "envswitch" persistence + layer that wins on next boot if you don't also write to it. **We must always + issue both.** +2. **margeServerUrl path is bare for `soundtouch-service`.** We mount the marge + endpoints at the **root** of port 8000, matching what the existing XML + migration writes (`Manager.migrateViaXML` in `pkg/service/setup/setup.go` + sets `MargeServerUrl: targetURL` without any suffix). Some community + recipes appended `/marge` because they were targeting + [`deborahgu/soundcork`](https://github.com/deborahgu/soundcork), which + routes marge under that sub-path. **For our service: bare URL. For users + redirecting to soundcork: append `/marge`** to both `margeServerUrl` and + the first argument of `envswitch boseurls set`. +3. **Each command must be sent one at a time, waiting for the device's `OK` + response** before sending the next one (`foob61451`'s explicit warning). + +### 2.2 Account pairing fallback + +`envswitch accountid set ` was reported by `bveenker` (#221) as an +in-band equivalent to the HTTP `/setMargeAccount` call, useful when the +`/setMargeAccount` endpoint is missing on the firmware (see §3). + +### 2.3 Probing / preflight + +- A bare TCP connect to `:17000` answers (no auth) on devices we care + about. +- Useful read-only verification command: `getpdo CurrentSystemConfiguration` — + prints the URLs after the changes have been applied so we can verify before + rebooting. +- `sys reboot` is the trigger that re-reads both layers. + +### 2.4 What Telnet:17000 cannot do + +- It does **not** install a custom CA. So if a user wants HTTPS rather than HTTP + redirection to our service (the DNS-method scenario, where `resolv.conf` + redirection collides with the device's TLS validation unless our root CA is + trusted on the device), telnet alone won't cover it. This is fine for our + default flow, which uses plain `http://` URLs to the service's port 8000. +- It does not give us a way to read or write `Sources.xml` (third-party + account credentials) — that still requires SSH, but for a migration we don't + actually need it. + +--- + +## 3. The `/setMargeAccount` problem (issue #236, #228) + +### 3.1 What it is + +A factory-reset speaker has an empty `` in `:8090/info`. The +marge endpoints fail with 502 / unhandled until that field is populated, which +is why several users (#221, #236) saw **everything except AUX** broken after +migration: + +``` +POST http://:8090/setMargeAccount +Content-Type: application/xml + + + 1234567 + soundcorkdoesntcare + +``` + +The values are not validated by the local service, so any numeric `accountId` +will work — soundcork's runbook (#228) literally calls the token +`soundcorkdoesntcare` to make the point. + +### 3.2 Why it's broken in practice + +There are **three independent failure modes** observed: + +| Symptom | Cause | Detection | +|-----------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------| +| Endpoint returns 404 / "not implemented" | Newer firmware (e.g. some BST20 Portable, latest ST Portable) drops the endpoint entirely. | `GET /supportedURLs` does **not** list `/setMargeAccount` in ``. | +| Endpoint hangs (no response / socket stays open) | "Broken state" the user explicitly called out — endpoint advertised, but handler is wedged. | Caller has to time out; we currently have no timeout, so the request appears to hang the migration UI indefinitely. | +| `POST /marge/streaming/support/power_on` → 502 unhandled (#236) | Device keeps polling marge after migration but no `margeAccountUUID` was ever assigned, so all subsequent calls fail. | `:8090/info` shows `` empty after reboot. | + +### 3.3 Required handling + +Per the user's brief, the migration logic must: + +1. **Probe** `GET http://:8090/supportedURLs` and check whether + `/setMargeAccount` is in the list **before** trying to POST it. +2. **Time-bound** the POST aggressively (e.g. ≤5s connect + ≤10s read) and treat + anything over the budget as a failure rather than waiting indefinitely. +3. On either failure mode, **fall back** to the telnet equivalent + (`envswitch accountid set ` + `sys reboot`). +4. If telnet:17000 is **also** unreachable, surface a clear "your firmware does + not support unattended pairing — please pair manually via the official Bose + app *before* it goes EOS, or open SSH and use the XML method" error rather + than leaving the device in a half-migrated state. + +### 3.4 Where the `` comes from + +The device's current account ID is already discoverable through endpoints we +control: + +- **`GET :8090/info`** returns `…`. If it + is non-empty the device is already paired — **reuse that ID**, do not + reassign. Our local marge accepts any ID, so the existing one is fine. +- If it is empty (factory reset), the user picks one in the UI: + 1. **Pick from existing accounts.** The setup UI lists IDs returned by + `DataStore.ListAccounts()` so a user can re-attach a fresh device to an + account that already has presets/recents/sources. + 2. **Enter manually.** Free-form text input, validated as **exactly 7 + numeric digits** (the format every Bose-cloud-issued ID has had in the + captures we've seen, and the format the wider community uses in their + recipes). + 3. **Randomize.** A "Generate" button that picks a 7-digit number and + re-rolls if it collides with an existing account in the local datastore. +- **Telnet read-back (best-effort).** `envswitch accountid get` is plausible by + symmetry with `envswitch accountid set` (#221) but is not yet confirmed + across firmwares. We will probe it during preflight; if it returns a value + we cross-check it against `:8090/info` and warn on mismatch. + +This means the user is never *forced* to invent a number — the common path is +"the device already has an ID, reuse it" — and the manual/randomize controls +only show up when the device is genuinely fresh. + +--- + +## 4. Port 17000 availability + +The diagnostic shell is gated by firmware build and product family. Anecdotally: + +- ST 10 / ST 20 / ST 300 / Wave III / Wave IV on FW 27.0.6 → **open**. +- SA-5 with FW 9.x → some commands present (`local_services on`) but + **no `remote_services on`** and no SSH on FW 9.0.43.23466 (#141). +- Modern firmware on some Portables → endpoint set has shrunk further. + +Because of this, we cannot assume port 17000 is reachable. The migration flow +must: + +1. **Probe** with a TCP connect to `:17000`, with a tight timeout + (≤2s). A successful TCP handshake is necessary but not sufficient — some + hardened firmware closes the port immediately. +2. **Banner check.** After connecting, read whatever the device sends within + ~1s. The diagnostic shell prints a small banner (firmware-dependent); a + blank read or an immediate close means we should treat it as "telnet not + usable" and disable the option. +3. **Capability check.** Issue a no-op like `getpdo CurrentSystemConfiguration` + and look for any non-empty response. If the device replies "Command not + found" we abort and suggest XML or DNS instead. +4. **Surface state to the UI.** The migration form should grey out the Telnet + option when the probe fails and show *why* (closed, banner missing, + command rejected) instead of letting the user click into a dead end. + +--- + +## 5. Implementation feasibility — Telnet client in Go + +This is a feasibility check only; no code is written yet. + +### 5.1 Protocol + +"Telnet" on port 17000 is effectively a line-oriented plain-TCP shell. The +device prints a small prompt (`->` in the SA-5 captures from #141) and reads +newline-terminated commands. There is **no** real Telnet option negotiation +(no `IAC`/`DO`/`WILL` exchanges visible in the wild captures), so we don't +need `golang.org/x/crypto/ssh`-class machinery. + +### 5.2 Standard-library only + +A minimal client is just `net.DialTimeout("tcp", host+":17000", 2*time.Second)` + +`bufio.Scanner` + `time.Time`-based deadlines on `Conn`. No third-party Telnet +library is needed; `github.com/reiver/go-telnet` would be overkill and adds +maintenance surface for no benefit. This matches the project's KISS principle +in `docs/CLAUDE.md` §3. + +### 5.3 Cross-platform compatibility + +`net.Dial` over TCP works identically on Windows, macOS, Linux and (with +limitations on listening) WASM. WASM-side: `soundtouch-service` runs server-side +anyway, so this only matters for `soundtouch-cli`, where TCP dial works in any +target other than browser-WASM — an acceptable carve-out documented separately. + +### 5.4 Concurrency / safety + +Each migration is a single goroutine driving one device. The client must: + +- enforce per-command response deadlines so a wedged device cannot stall the + migration UI (mirrors the `/setMargeAccount` requirement); +- never send `sys reboot` until **all** preceding `OK` acks have arrived (so + partial config doesn't get persisted); +- always close the socket on error. + +### 5.5 Testing strategy + +We can test without a real speaker by spinning up a `net.Listen("tcp", "127.0.0.1:0")` +in the test, scripting it to consume our commands and emit canned `OK`/error +responses. That gives us deterministic coverage for: + +- happy path (all four URLs accepted), +- single-command failure → no `sys reboot` sent, +- "command not found" on `envswitch …` → fallback path exercised, +- TCP closed mid-stream → migration aborts cleanly, +- read deadline triggers when the device hangs (the broken-state simulation). + +The repo already follows the "real device responses preferred, mock servers +otherwise" rule (see `docs/CLAUDE.md` §1, §8). The tests above are the mock-server +half of that pattern. + +### 5.6 Where it lives + +The protocol client is **a standalone package**, not buried inside +`pkg/service/setup`, so it can be reused from CLI tools, future setup wizards, +and tests without dragging the migration manager in: + +``` +pkg/telnet/ # NEW reusable package + client.go # Dial / SendCommand / Probe / Close + client_test.go # mock-server tests against a net.Listen + +pkg/service/setup/ + telnet_migration.go # NEW thin wrapper that imports pkg/telnet + # and runs the URL config sequence + marge_pairing.go # NEW /setMargeAccount probe + post + telnet + # `envswitch accountid set` fallback + setup.go # add MigrationMethodTelnet const + case +``` + +UI plumbing is `pkg/service/handlers/web/index.html` (option list) and +`pkg/service/handlers/web/js/script.js` (`toggleMigrationMethod()`). The +deprecated `hosts` option is already hidden from the dropdown when we ship +this; we just add a `telnet` option next to `xml`/`resolv`. + +### 5.7 Verdict + +**Feasible and small.** Estimated scope: ~200 lines of client code in +`pkg/telnet`, ~300 lines of tests, plus a `MigrationMethodTelnet` branch in +`Manager.MigrateSpeaker`, plus the preflight probe described in §4 and the +`/setMargeAccount` guarding described in §3. + +--- + +## 6. Decisions made (was: open questions) + +1. **Account-ID generation.** Resolved — see §3.4. The migration form reads + `:8090/info` first; if `margeAccountUUID` is non-empty it is reused. + Otherwise the UI offers (a) pick from `DataStore.ListAccounts()`, + (b) manual entry validated as 7 numeric digits, (c) a "Generate" button + that randomizes a 7-digit number and re-rolls on collision. +2. **Reboot policy.** Migration is automatic, but the UI shows a **modal + confirmation** before the final `sys reboot` is sent ("Speaker will reboot + now to apply changes — continue?"). This matches the XML path, which + already reboots automatically, while preventing surprise reboots from a + stray click on a half-filled form. +3. **CA / HTTPS story.** Telnet has no way to install a custom CA. Documented + as an explicit limitation: telnet method = HTTP-only redirect to our + service. Users who need end-to-end TLS must use the XML or DNS method. + *Possible future enhancement* — a hybrid "install CA via SSH/XML, then drive + the URL flip via Telnet" path. Feasibility unknown; not in this iteration. + +--- + +## 7. Summary of what changes when this lands + +- **New reusable package `pkg/telnet`** — line-oriented TCP client with + `Dial`, `SendCommand`, `Probe`, `Close`, all deadline-driven. No external + dependencies, usable from CLI, service, and tests. +- **New `MigrationMethodTelnet = "telnet"`** constant in `pkg/service/setup/setup.go` + plus a `migrateViaTelnet` branch in `Manager.MigrateSpeaker`. +- **New `pkg/service/setup/telnet_migration.go`** orchestrating the URL + configuration sequence (§2.1) on top of `pkg/telnet`. +- **New `pkg/service/setup/marge_pairing.go`** with `PairAccount(deviceIP, id)`: + probes `/supportedURLs`, time-bounded `POST /setMargeAccount`, falls back to + telnet `envswitch accountid set ` on missing/wedged endpoint. +- **`MigrationSummary` gains** `TelnetReachable`, `TelnetBanner`, + `TelnetCommandsAccepted`, `SetMargeAccountSupported`, `CurrentAccountID`, + `KnownAccountIDs` so the UI can show preflight outcomes and offer reuse. +- **UI** — `web/index.html` dropdown gets a `telnet` option (greyed out when + preflight fails) and a new pane for picking/entering/randomizing a 7-digit + account ID when `:8090/info` reports an empty `margeAccountUUID`. A modal + confirmation gates the final `sys reboot`. The legacy `hosts` option stays + out of the dropdown (deprecated).