docs(local-model): label the route experimental and write down the rules

- docs/api-reference.md: GET /api/local-model is labeled experimental
  until the step that sets a model up ships, so its payload is not a
  stable /api/v1 contract one stage before that step changes it. The
  section now describes the verdict as judged, the three sentences of
  the memory reason, the notes, the speed rounding and which size to
  show as the installed memory. The os-fallback description was wrong:
  the free disk space is reported there too.
- docs/versioning-policy.md: the route is listed under the experimental
  surfaces.
- docs/wiki/Settings-Reference.md: App Settings > Models > Model on this
  Mac, in the words of a user.
- CLAUDE.md and src/web/CLAUDE.md: the invariants the code relies on
  (read-only, the probe, harness rows as data, the meaning of limited,
  the word Recommended, one unit, labels from the payload, when the
  card and the group show).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

CLAUDE.md

@@ -191,6 +191,8 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 ⚠️ **llama-swap endpoints** (one model at a time): the apply routes check `GET /running` and return `requiresConfirmation` before evicting a model another live session uses; `confirmedSwap` and `confirmedContext` are SEPARATE flags and must stay so. Claude alone gets a context floor (`CLAUDE_MIN_SAFE_CONTEXT_TOKENS`); context is parsed from `/running`'s `cmd`, never trusted from `/props`. The floor also divides that context by the model's parallel slot count (`modelSlotCounts`: `--parallel`/`-np` from `cmd`, else `/props` `total_slots`; `perSlotContext()`), and `/props` only ever RAISES that warning: it supplies the context only when `cmd` states none and the count only when `cmd` has no `--parallel`, never a larger pool. `/props` is probed once per launch command (it refreshes llama-swap's last-use time, so a `ttl` would never expire), and a `/props` context beside an explicit `--parallel N` is already per slot, so it is not divided again. Backend log lines come from llama-swap's `/api/events` `upstream` source, never `/logs`. → [architecture-invariants#custom-model-endpoint-profiles](docs/architecture-invariants.md#custom-model-endpoint-profiles)
 
+**Local model recommendation** (`GET /api/local-model`, `src/local-model/`, `src/config/local-model-catalog.ts`, `src/types/local-model.ts`; EXPERIMENTAL, read-only stage): the server looks at the Mac it runs on and says which local coding model fits it and with which agent CLI. ⚠️ **Read-only**: it downloads nothing, installs nothing, writes no file and adds no settings key; the install flow is a later stage and nothing here may grow a write before it. Apple silicon macOS only: anywhere else the answer is a `200` with verdict `none` (reasons `not-macos`, `intel`, `memory`, `disk`, `macos`, `no-harness`), and a failed probe is an answer, never a 500. The probe (`hardware.ts`) is ONE bounded async spawn of `/usr/sbin/sysctl` WITHOUT `-n`, parsed as `key: value` lines by the pure `parseSysctl()`, plus `statfs` of the data dir (probed bounded first, #516) and `node:os` fallbacks, cached 60 s; ⚠️ never `system_profiler`, never a second spawn, and `iogpu.wired_limit_mb` of 0 means not set. The catalogue is a compiled constant validated by a Zod schema: ⚠️ no override file and no runtime data, and a model id is `name:tag` in lowercase with no slash (`LOCAL_MODEL_ID_PATTERN`). ⚠️ A harness is a catalogue ROW (`{ cli, minContext, rank, gated?, slowFirstTurn? }`) plus a `HarnessFact` built from the CLI registry at call time (`harness-facts.ts`); no code compares a CLI id (both id-branching guards scan these files). `recommend()` (`recommend.ts`) is pure. ⚠️ `limited` is a statement about the MAC (no model with 12 billion parameters or more fits), judged before the disk filter and whatever the pick is; a small pick under `ok` carries `noteSmallPick`, and a model left out for disk space is named in `noteDiskDropped`, never dropped in silence. ⚠️ The word "Recommended" exists only in `headlineTested` and is sent only when the pick's model has a `tested` entry for exactly this chip, memory size and harness; no row has one today. ⚠️ Speed is `ok`/`slow`/`unknown`, graded on the unrounded figure, and a chip in no chips row is `unknown`: never guess a bandwidth. ⚠️ ONE unit for every computed size a person reads: decimal GB text from `formatGb()` (`format.ts`), sent beside the bytes, and the browser never divides bytes; the one exception is the installed memory, shown as `memClassGb` (the size the Mac is sold as, 48 and not 51.5). ⚠️ Every sentence the server chooses is a `LOCAL_MODEL_LABELS` text with `{placeholder}` slots filled from `vars` (no apostrophe in a text: the zh-CN key is single-quoted), and each needs a zh-CN entry. Admin only in multi-user mode (403 before anything is probed). Tests: `test/local-model-*.test.ts`, `test/routes/local-model-routes.test.ts`. Card rules: `src/web/CLAUDE.md` (Model on this Mac). → `docs/api-reference.md` (Local model recommendation), `docs/versioning-policy.md`
+
 **MCP server sync** (opt-in, `mcpSyncEnabled`, SYNCED, default OFF; `src/mcp-sync.ts`, `GET`/`POST /api/mcp-sync`): copies each installed, enabled CLI's user-level MCP servers into the others. It is the ONE subsystem that writes another CLI's REAL user config (`~/.claude.json`, `~/.codex/config.toml`, `~/.gemini/*`, opencode's), which is why it is opt-in and admin-only in multi-user mode (both verbs 403 for a non-admin, and the Settings group is hidden for them). Where each CLI keeps the file is registry data, `capabilities.mcpConfig` (`{ path, format, relocation? }`), never a branch on the id. ⚠️ Tools that sync but are not run modes (GitHub Copilot CLI, the first) are plain data in `MCP_SYNC_ONLY_TOOLS` (`src/mcp-sync-targets.ts`), take part only when installed or already configured, and their companion `settings.json` (`disabledMcpServers`) is read, never written; a test must clear their relocation vars too. ⚠️ ADDITIVE only: a name already defined, in any shape, is never edited or removed (a different same-name definition is a reported conflict), and a server switched off in its own CLI is never copied. ⚠️ Never write a file that did not parse; re-parse the NEW text and require every added server to read back before the tmp+rename (written through a symlink, previous file kept as `<file>.codeman-bak`, one apply at a time, else 409). ⚠️ A file that receives copied `env`/`headers` (secrets) is left `0600`, and so is the backup. ⚠️ Responses carry server NAMES only, never env values, headers or file text: a parse failure is reported by line and column (`describeMcpSyncError`), never the parser's own message (smol-toml and V8 both quote source). ⚠️ `mcpConfig.relocation` names the env var the CLI reads to move its file (`CLAUDE_CONFIG_DIR`, `CODEX_HOME`, `XDG_CONFIG_HOME`, `GEMINI_CLI_HOME`, and `COPILOT_HOME` for Copilot), resolved from the SERVER env at call time; a relative value reports the target `skipped`, never a guessed write, and a per-session `envOverrides` relocation is not followed. Tests must pass `home` (which drops the `process.env` default) or clear those vars first. → `docs/cli-registry.md` (MCP server sync), `docs/api-reference.md`, `docs/wiki/Settings-Reference.md`
 
 **Auto-named sessions** (`autoNameSessions`, SYNCED, default OFF): a placeholder tab (`w3-myapp`) takes its first real prompt as a title in the `<prefix>: <title>` form, so the case identity and `w<n>` counter survive. Ownership is `SessionState.nameSource` (`placeholder` | `auto` | `manual`; the `name` setter / `PUT /api/sessions/:id/name` makes it `manual`, never touched again). ⚠️ `applyAutoName()` flips to `auto` even if the string is unchanged, so only the FIRST titled prompt names the tab. ⚠️ Only user input counts: `SessionWriteOptions.fromUser` is set by the browser WS path, `POST /api/sessions/:id/input`, the experimental guarded stage (`stageGuardedInput()`, `POST /api/sessions/:id/stage`, typed on an agent's behalf like the input route) and a Discord reply (`DiscordBridge.onGatewayMessage`, through the bridge's `sendInput`) ONLY; any new user-input path must set it (and the send-key Shift+Enter path must call `trackUserInput()`). ⚠️ The pure tracker (`session-auto-name.ts`) sits on the raw keystroke stream with an explicit rule per key; add a rule for any new key class. ⚠️ `nameSource` also decides `--name`: by default only a `manual` name is pinned on the claude CLI (`Session.cliPinnedName`), since `--name` is also the `/resume` title and a pinned one stops Claude generating its own; the opt-in synced `pinCliSessionName` (default OFF, re-read at every spawn and respawn) pins every tab name, after which a Codeman rename holds only until the next turn; a rename appends a `custom-title` row to a LOCAL, non-docker transcript, and a same-name PUT is a no-op (never flips to `manual`). Tests: `test/session-auto-name.test.ts`. → [architecture-invariants#auto-named-sessions-first-prompt--tab-title](docs/architecture-invariants.md#auto-named-sessions-first-prompt--tab-title)

docs/api-reference.md

@@ -1680,6 +1680,8 @@ Only replies from `allowedUserIds`, in `guildId`, inside a thread the bridge cre
 
 `GET /api/local-model` looks at the machine the server runs on and says which local coding model fits it, and with which agent CLI. It covers Apple silicon macOS only; anywhere else the answer is still a `200`, with verdict `none`. **Read-only:** the route downloads nothing, installs nothing, writes no file and reads or changes no setting (setting a model up from Codeman is a later step and is not built yet). It names the host's hardware, so it is admin only in multi-user mode (`403`, answered before anything is probed). The models, their sizes and the agent CLIs it considers are a catalogue compiled into the release; there is no override file.
 
+**Experimental.** This endpoint and its payload are labeled experimental until the step that sets a model up ships: that step will add to and may change the fields below, the verdicts and the sentences, in a MINOR or PATCH release (see [versioning-policy.md](versioning-policy.md), "What SemVer does NOT cover", item 3). Do not build on its shape yet.
+
 | Method | Path               | Body | Notes                                                                                                                                                                                                    |
 | ------ | ------------------ | ---- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `GET`  | `/api/local-model` | none | `200` with `{ hardware, recommendation, catalogUpdated }`. `403 FORBIDDEN` for a non-admin in multi-user mode. `500 INTERNAL_ERROR` only when the recommendation itself fails, never for a failed probe. |
@@ -1690,24 +1692,24 @@ A probe that fails is an answer, not an error: a server that is not on macOS, or
 
 - `hardware`: what the server sees of the machine it runs on.
   - `platform`, `arch`: `process.platform` and `os.arch()` of the server process. `arm64: true` means the machine is Apple silicon whatever `arch` says; `translated: true` means the server process runs under Rosetta.
-  - `memBytes`, `memGb` (decimal GB text) and `memClassGb` (the memory size the Mac is sold as: 16, 32, 48).
+  - `memBytes`, `memGb` (the bytes as decimal GB text, `"51.5"` for a 48 GB Mac) and `memClassGb` (the memory size the Mac is sold as: 16, 32, 48; `0` when the size could not be read). `memClassGb` is what to show as the installed memory: it is the number on the box and in About This Mac. It is the one size here that is not decimal GB.
   - `chip`, `model`, `macosVersion`, `macosMajor`, `wiredLimitMb` (`0` means not set), `freeDiskBytes` and `freeDiskGb` (free space on the filesystem of Codeman's data directory). Each is absent when it could not be read.
-  - `source`: `sysctl` (the one bounded `sysctl` call answered), `os-fallback` (macOS, but that call failed, so only memory, architecture and the chip name are known) or `not-probed` (not macOS, nothing was run).
+  - `source`: `sysctl` (the one bounded `sysctl` call answered), `os-fallback` (macOS, but that call failed: memory, architecture, the chip name and the free disk space come from Node, and nothing only `sysctl` knows, such as `arm64`, `translated`, `model`, `macosVersion`, `macosMajor` or `wiredLimitMb`, is present) or `not-probed` (not macOS, nothing was run).
 - `recommendation`:
-  - `verdict`: `ok`, `limited` (the best model that fits has fewer than 12 billion parameters: it handles small edits and questions and does not replace a cloud model) or `none`.
-  - `reason`, present only with `none`: `not-macos`, `intel`, `memory`, `disk`, `macos` (too old) or `no-harness` (no agent CLI that can be connected to a local model is installed or installable).
-  - `headline` and `notes[]`: `{ text, vars? }`. `text` is an English sentence that may hold `{placeholder}` slots, and `vars` carries the slot values as text.
-  - `pick` (absent with `none`) and `alternatives[]` (at most four, best first; empty with `none`), each one model at one context length with one agent CLI:
+  - `verdict`: `ok`, `limited` or `none`. `limited` is a statement about the Mac: no model with 12 billion parameters or more fits its memory, so what it can run handles small edits and questions and does not replace a cloud model. It is judged on every model that fits, before the free disk space is looked at and whatever the pick is. With `ok` the pick can still be a small model (a larger one may fit only tightly, have no speed figure or have no room on the disk); `notes` then says so.
+  - `reason`, present only with `none`: `not-macos`, `intel`, `memory`, `disk`, `macos` (too old) or `no-harness` (no agent CLI that can be connected to a local model is installed or installable). `memory` has three sentences: nothing fits at all (slot `memory`, the size the Mac is sold as), a model fits but only below the context length an agent CLI needs (slots `budget` and `need`, so a Mac that misses by a little reads as that), and the memory size could not be read (no slot).
+  - `headline` and `notes[]`: `{ text, vars? }`. `text` is an English sentence that may hold `{placeholder}` slots, and `vars` carries the slot values as text. Notes, in order: the pick is a small model although larger ones fit (verdict `ok` only); a model that fits the memory was left out because its download would not leave 10 GiB free on the disk (slots `model` and `missing`: the best-ranked such model and the GB to free up); nobody tested the pick on a Mac like this one.
+  - `pick` (absent with `none`) and `alternatives[]` (at most four, best first; empty with `none`), each one model at one context length with one agent CLI. A model whose download would leave less than 10 GiB free on the disk is not listed (an unknown free disk space excludes nothing):
     - `modelId` (`name:tag`), `modelLabel`, `license`, `paramsB` (parameters in billions), `context` (tokens);
     - `cli`, `cliLabel`, `cliInstalled` (`false`: the CLI is not on this machine yet but can be installed without administrator rights), `slowFirstTurn?`;
     - `needBytes` and `needGb` (memory the model needs at that context), `downloadBytes` and `downloadGb`, `budgetShare` (need divided by `budgetBytes`, rounded to three decimals);
     - `fit`: `good` (up to 0.85 of the budget) or `tight` (up to 0.98), with its label `fitLabel`;
-    - `speed`: `ok`, `slow` or `unknown`, with `speedLabel` (absent for `ok`) and `tokensPerSecond` (absent for `unknown`). `unknown` means the chip is in no row of the catalogue's chip table, or the catalogue has no speed figure for the model: a speed is never guessed;
+    - `speed`: `ok`, `slow` (under 10 tokens per second) or `unknown`, with `speedLabel` (absent for `ok`) and `tokensPerSecond` (rounded to one decimal, absent for `unknown`; `speed` is decided on the unrounded figure, so `10` can be `slow`). `unknown` means the chip is in no row of the catalogue's chip table, or the catalogue has no speed figure for the model: a speed is never guessed;
     - `tested`: we ran this model with this CLI on a Mac like this one. No catalogue row has such an entry yet, so it is `false` today.
   - `budgetBytes` and `budgetGb`: the memory a model may use on this Mac (`0` for `not-macos` and `intel`, where none is computed). `budgetSource` is `wired-limit` (taken from `iogpu.wired_limit_mb`) or `estimated` (computed from the installed memory).
 - `catalogUpdated`: ISO date on which the catalogue's rows were last checked.
 
-Every size a person reads travels twice: as bytes, and as decimal GB text without the unit (`"needGb": "29.6"`). Show the text and add the unit; do not divide the bytes yourself, so one request never shows two different roundings.
+Every computed size a person reads travels twice: as bytes, and as decimal GB text without the unit (`"needGb": "29.6"`). Show the text and add the unit; do not divide the bytes yourself, so one request never shows two different roundings. The installed memory is the exception named above: show `memClassGb`.
 
 ## Voice dictation
 

docs/versioning-policy.md

@@ -86,6 +86,19 @@ covered like any other stable behavior. Other agent commands and API routes keep
 their existing guarantees. Promotion to stable requires an explicit documented
 decision.
 
+### Experimental local model recommendation
+
+`GET /api/v1/local-model` (and its `/api` alias) is labeled experimental, so item 3
+above applies to it: its path, its payload (the hardware facts, the verdicts and
+reasons, the candidate fields and the English sentences in `headline` and
+`notes`) and its behavior may change or be removed in a MINOR or PATCH release.
+It is read-only today: it looks at the Mac the server runs on and says which
+local model fits. The step that sets a model up from Codeman is not built yet
+and will change what the route reports, which is why the shape is not promised.
+It is not behind a setting (it writes nothing and adds no settings key); it is
+admin only in multi-user mode. Promotion to stable requires an explicit
+documented decision.
+
 ## Deprecation policy
 
 When we need to change a covered surface:

docs/wiki/Settings-Reference.md

@@ -193,6 +193,20 @@ attached.
 section to the Run dropdown, for pointing a harness at your own OpenAI-compatible server
 instead of its native cloud backend. See [Custom Model Endpoints](Custom-Model-Endpoints).
 
+**Model on this Mac** is not a setting: it is a read-only answer. When the Codeman server
+runs on a Mac with Apple silicon, it shows that Mac's chip, memory and free disk space, the
+local coding model that fits it best with the agent CLI to run it, what the model needs of
+the memory the Mac can give one, its download size and an estimated speed, and the other
+models that fit (Good or Tight for the memory, Slow or Speed unknown for the speed). A Mac
+that can only run a model under 12 billion parameters is told so in plain words, and a Mac
+with too little memory, too little free disk space or an Intel processor is told why nothing
+is offered. The numbers are estimates from a catalogue that ships with each release; nothing
+has been tested on your Mac. **Nothing is downloaded or installed from here yet**: setting
+the model up from Codeman is the next step and is not built. The same answer appears as a
+card on the welcome screen, which you can hide per device (it stays here). The group is not
+shown when the server runs on Linux or Windows, and in multi-user mode only an admin sees
+it. The "Mac" is always the machine the server runs on, not the device you are reading on.
+
 ### Agents & CLIs
 
 | Setting                          | Notes                                                                                        |

src/web/CLAUDE.md

@@ -48,6 +48,8 @@ Frontend JS modules have `@fileoverview` with `@dependency`/`@loadorder` tags. L
 
 **Opened outside Codeman** (`foreign-sessions.js`, both home screens): the tmux sessions a human started, listed from `GET /api/mux/foreign` (root CLAUDE.md, Adopted tmux sessions). ONE renderer, `renderForeignSessions(container)`, fills the welcome block and the phone overview's, and every row goes through `textContent`, since a session name and a command line come from someone else's process. ⚠️ It polls only while a home screen is up (`startForeignPolling`/`stopForeignPolling` from `showWelcome()`/`hideWelcome()`) and the tab is visible (`_foreignPollTick()` is the one gate, and `visibilitychange` catches up; the cache TTL sits under the poll interval, so one tab's every tick is a full socket sweep), and the poll is local only: the docker and ssh scan costs one connection per target, so it runs once on the toggle and again on Rescan, and its rows and notes are kept apart (`_foreignWideSessions`, `_foreignWideNotes`) or the next local poll would wipe them. ⚠️ A 403 is a non-admin in multi-user mode, an answer and not a failed poll: `_foreignRefused` stops the polling and shows no block. ⚠️ `closeSession()` re-reads the list after an adopted tab's DELETE, since the home screen's own load races it and the row would say `Go to tab` until the next poll. ⚠️ An adopted tab has no kill outcome to offer, so the close dialog hides the red button and always tears the wrapper down. ⚠️ `session.remote` and `session.docker` are undefined on an adopted session, so a check that hides a row for those two usually needs `session.adopt` as well. Tests: `test/foreign-sessions-ui.test.ts`, `test/foreign-sessions-i18n.test.ts` (harvests every string from the real module).
 
+**Model on this Mac** (`local-model-ui.js`; welcome card `#localModelCard` + App Settings > Models group `#localModelGroup`; server rules in the root CLAUDE.md, Local model recommendation): a READ-ONLY view of `GET /api/local-model`. ONE builder (`localModelBody`) paints both containers, so the card and the Settings row can never name a different pick; the card folds the alternatives, Settings lists them. ⚠️ Every dynamic string goes in through `textContent` (model, harness and chip names are someone else's text), both containers carry `data-i18n-skip`, and the module translates its own sentences at render time, so a language or display-name change must repaint from the module (the `<html lang>` observer). ⚠️ Labels and sentences come from the payload (`{ text, vars }` through `localModelT`); the module holds no list of models or harnesses, never compares a CLI id, and never contains the word "Recommended" (that headline is the server's to send). ⚠️ `test/local-model-i18n.test.ts` harvests every `localModelT('...')` literal: a new string is a single-quoted literal with no apostrophe and gets a zh-CN entry, and the only non-literal calls are the two payload ones. ⚠️ Sizes are printed as sent (decimal GB text), bytes are never divided here; the installed memory alone is `memClassGb`, a number or nothing (an unknown size is left out, never `0 GB`). ⚠️ The card ships `hidden` and shows only once the server answered for a Mac; the card AND the Settings group stay hidden for `not-macos` (the server is usually Linux, and "this Mac" always means the machine the server runs on), for a refusal and while the first request is in flight; a failed first request shows one sentence in Settings only. ⚠️ Refused means `403` with `errorCode: FORBIDDEN` (a non-admin in multi-user mode: stop asking); the auth layer's `403 PASSWORD_CHANGE_REQUIRED` is a failed request that is asked again on `codeman:me`. ⚠️ Each fit and speed pill carries what it measures as `title` + `aria-label` ("Good" is the memory fit, not a rating), and the line saying Codeman cannot download or install yet sits right under the pick and its notes, in `--text-dim` like every other line. The dismissal is a per-device localStorage key named for this stage (`codeman:local-model-dismissed:readonly`), never a server setting: the stage that can set a model up takes a new key so its offer shows once more. At most one request a minute (the server caches its probe for 60 s), shared while in flight, and a failed refresh keeps the answer on screen. Tests: `test/local-model-ui.test.ts`, `test/local-model-i18n.test.ts`.
+
 **Home-screen session order** (`CodemanSessionOrder` in constants.js, pure): BOTH home screens (phone overview, desktop rail) must order rows through this ONE comparator. Rank `needs` → `error` → `waiting` → `working` → `idle` → `done`. ⚠️ The tiebreak flips: states a session is still IN sort oldest-first, states it has STOPPED sort newest-first. ⚠️ The running group keys off `lastSubmitAt`, never `lastActivityAt` (a working pane repaints constantly). ⚠️ A 0 stamp means unknown and sorts last within its state. Final tiebreak is `orderIndex`, so the list never shuffles. The tab strip itself is NOT sorted by this. Test: `test/session-overview-order.test.ts`. → [architecture-invariants#home-screen-session-order](../../docs/architecture-invariants.md#home-screen-session-order)
 
 **Welcome "Resume Conversation" list** (terminal-ui.js): `loadHistorySessions()` fetches once and caches the corpus on `_historyAll`/`_historyCases`; every subsequent view (filter box, sort select, expand, the periodic refresh in panels-ui.js) goes through `_renderHistoryList()`, so never append rows to `#historyList` directly or re-fetch to re-sort. ⚠️ The box height is **class-driven**: expanding the list without `.history-list.expanded` leaves the collapsed `max-height` in place and just deepens a scroll well, which is the bug #260 reported (35 sessions in a ~4-row box). ⚠️ The A–Z sort keys off `_historyRowLabel()`, the SAME string the row renders (`name || firstPrompt || path`), most rows are transcript-backed and have no session name, so sorting on `name` alone silently does nothing. ⚠️ A filter implies expansion, and `_renderSearch()` hides `#historyHeader` (title + controls) as one unit while a search is active. Tests: `test/history-list-controls.test.ts`.

src/web/routes/local-model-routes.ts

@@ -6,6 +6,11 @@
  * `{ hardware, recommendation, catalogUpdated }`. Nothing is reformatted here: every size text
  * and every sentence in the payload was chosen by the modules that produced it.
  *
+ * EXPERIMENTAL (docs/versioning-policy.md, "Experimental local model recommendation"): the
+ * route and its payload are outside the stable `/api/v1` contract until the stage that sets a
+ * model up ships, because that stage will change what the fields mean. docs/api-reference.md
+ * says so in its section; keep the two in step, and drop both labels together.
+ *
  * Rules:
  *  - Read-only. It downloads nothing, installs nothing, writes no file and reads no setting.
  *  - A failed probe is an answer, never a 500. `readHardware()` reports a spawn that failed