# Cowork probe

Plan Step 1 (M1). An empirical record of what this operator's Cowork
installation actually does, measured before any code depends on it.

Operator decision 7 — Python as a CLI plus a host-side stdio MCP server — is
void if host-side servers never appear in a Cowork session. That is not
knowable from Claude Code, so it is measured here first, and the milestone that
depends on it carries a written degradation branch either way.

**Status: unanswered.** All four questions require the operator sitting in a
Cowork session on this Mac. The executor session built the probe vehicle and
this checklist; it did not and could not answer them. The verify command for
this step is written so an unanswered checklist *fails*:

```bash
test "$(grep -cE '^- (Sesjonsmodus|Host-MCP|python3|CLAUDE_PLUGIN_ROOT): +(lokal VM|sky|ja|nei)\b' docs/cowork-probe.md)" = 4
```

A bullet still reading `ubesvart` does not match, the count drops below four,
and the command exits non-zero. That is the intended behaviour until the
operator has run the probe.

## Results

Overwrite `ubesvart` with one of the allowed answers, and put the date of the
measurement in the Measured column. A `nei` is a result, not a failure — it
selects the degradation branch below.

- Sesjonsmodus: ubesvart
- Host-MCP: ubesvart
- python3: ubesvart
- CLAUDE_PLUGIN_ROOT: ubesvart

| Bullet | What the operator does in Cowork | Allowed answer | Measured |
|---|---|---|---|
| `- Sesjonsmodus:` | Open a Cowork session and read whether it is a local VM or cloud | `lokal VM` or `sky` | |
| `- Host-MCP:` | Upload `jobbsok-probe.plugin` via Customize -> Plugins; does `probe-tools` appear as a connector, and does `probe_ping` return? | `ja` or `nei` | |
| `- python3:` | Run the `probe-versjon` skill; does it succeed in invoking `python3`, and which version does it report? | `ja` or `nei`, followed by the reported version | |
| `- CLAUDE_PLUGIN_ROOT:` | Run `probe-versjon`; does it print a resolved absolute path, or the literal variable name? | `ja` or `nei` | |

### What is already known, and what is not

Measured 2026-09-04 from Claude Code, before the probe was built:

- Cowork is installed and available on this Intel Mac.
- The **session mode is not readable from disk.** `cowork_settings.json` carries
  only `extraKnownMarketplaces`; the desktop config carries `coworkNetworkMode`
  and a trusted-folder list, and neither states where a session runs. So
  `- Sesjonsmodus:` cannot be answered by reading files — it has to be read off
  a live session.
- The other three each require a plugin installed in a live Cowork session.
  Nothing about them is decidable from Claude Code.

## The probe vehicle

`jobbsok-probe` — a throwaway test plugin, deliberately **not** the `jobbsok`
plugin itself. `jobbsok`'s own `.mcp.json` (Step 12) and packaging script
(Step 13) land eleven steps later, and this probe must not wait for them.

It holds exactly four files, under `tests/fixtures/cowork-probe/`:

| File | What it is for |
|---|---|
| `.claude-plugin/plugin.json` | Manifest. Name `jobbsok-probe`, version `0.0.1`. The version is what `probe-versjon` echoes, so a mismatch reveals a cached build. |
| `skills/probe-versjon/SKILL.md` | A skill that reports the manifest version, the resolved `${CLAUDE_PLUGIN_ROOT}`, and whether it can invoke `python3`. Answers three of the four questions. |
| `.mcp.json` | Declares one stdio server, `probe-tools`. Its appearance in the session is the whole `- Host-MCP:` question. |
| `probe_tools.py` | Standard-library JSON-RPC server exposing one tool, `probe_ping`, returning the interpreter actually running it. No third-party imports: a server that failed on a missing dependency would answer a different question than the one asked. |

Verified from Claude Code 2026-09-04: the server completes an `initialize`
handshake, lists `probe_ping`, returns an interpreter version on
`tools/call`, and rejects an unknown tool name. What is unverified is whether
Cowork ever starts it.

### Building the archive

Run from the repository root. The file list is explicit, and that is the point:

```bash
cd tests/fixtures/cowork-probe && \
  zip -X /tmp/jobbsok-probe.plugin \
    .claude-plugin/plugin.json \
    .mcp.json \
    probe_tools.py \
    skills/probe-versjon/SKILL.md
```

Never `zip -r` over the repository root. A recursive archive of the repo would
ship `.git`, `STATE.md`, `.claude/` and the virtualenv into an uploaded plugin.
The include list above names the four files and can carry nothing else.

## Running the probe, step by step

Everything below happens in Claude Cowork on this Mac, not in Claude Code.
Where a UI path is named it comes from Anthropic's own documentation
(`research/03-cowork-plugin-compatibility.md`, dimensions 1 and 6); where the
wording in the app turns out to differ, trust the app and note what you saw --
a changed menu label is itself a finding worth recording.

### A. Read the session mode -> answers `- Sesjonsmodus:`

Open Cowork and find its session-location setting (Cowork -> Settings). You are
looking for whether sessions run **on this machine** or **in the cloud**.

- On this machine: shell commands execute in a dedicated local Linux VM
  (Apple Virtualization.framework), which needs working hardware
  virtualization; Claude runs a readiness check for exactly that.
- In the cloud: code runs on Anthropic's servers. This has been the default
  since 2026-07-07, so do not assume local just because the Mac is capable.

Write `lokal VM` or `sky`.

**Do this one first**, because it very likely decides question B below:
Anthropic's documentation states that local MCP servers do not run in cloud
sessions. If you answer `sky` here and `ja` to `- Host-MCP:`, that combination
contradicts the documentation and is a much more interesting result than either
answer alone -- say so in the Measured column.

### B. Install the probe plugin (needed for C, D and E)

Two documented routes; either is fine.

1. Customize -> Plugins, choose the install-from-file / upload option, and pick
   `/tmp/jobbsok-probe.plugin`.
2. Or drag the `.plugin` file into the Cowork chat. Anthropic's own plugin
   packaging skill says a `.plugin` file appears in the chat as a rich preview
   with a button to accept it.

Known wrinkle, not your mistake if it happens: uploaded plugins have been
reported not to survive an app relaunch (claude-code#65426, June 2026). If the
plugin disappears later, re-upload it rather than concluding anything about
the probe.

### C. Confirm you are testing the build you just uploaded

In the Cowork chat, type `/` (or `+`) to list available skills, and run
`probe-versjon`.

The first thing it reports is the manifest version. It must be **`0.0.1`**.

If it reports anything else, Cowork served a cached build rather than the one
you uploaded (claude-code#69020, open) -- and then every answer below is about
some *other* build. Uninstall, re-upload, and re-run before continuing. This
check exists because a stale cache produces confident, wrong measurements.

### D. Read the skill's output -> answers `- python3:` and `- CLAUDE_PLUGIN_ROOT:`

Both come from that same `probe-versjon` run.

**`- python3:`** -- did the skill succeed in running
`python3 -c 'import sys; print(sys.version)'`, and what did it print?
Write `ja` followed by the version, or `nei` followed by the error text.

One thing to be precise about, because it changes what the answer means: in
Cowork, shell commands run inside the sandbox (the local VM, or the cloud
environment), **not on your Mac**. So this measures the sandbox's `python3`,
not the host's. That is the right thing to measure here -- it tells us whether
a skill-invoked script can run in Cowork at all -- but it is not evidence about
the interpreter that `scripts/bootstrap.sh` just built a virtualenv for.

**`- CLAUDE_PLUGIN_ROOT:`** -- did the skill print a resolved absolute path, or
the literal unexpanded string `${CLAUDE_PLUGIN_ROOT}`? Write `ja` or `nei`.
An absolute path is the pass; anything literal or empty is `nei`.

### E. Look for the connector -> answers `- Host-MCP:`

This is the load-bearing one: it is the entire Cowork half of operator
decision 7, and the reason this probe is the first step of the build.

A server declared in `.mcp.json` does **not** show up as a skill. In Cowork it
appears as a **Connector**. Two checks, and both must hold:

1. **Is it listed?** Customize -> Plugins, open `jobbsok-probe`, and look at
   its connectors page. Is `probe-tools` there?
2. **Does it answer?** In the chat, ask Claude to call the `probe_ping` tool.
   It should return JSON containing `python_version` and `python_executable`.

Write `ja` only if both hold. If `probe-tools` is listed but never answers,
write `nei` and note that it appeared but did not respond -- a connector that
does not respond is not a working host-side server, and the difference between
"absent" and "present but mute" points at different causes.

Unlike D, this one *does* run on your Mac: Anthropic moved local MCP servers
out of the sandbox in May 2026 and runs them as ordinary host software. So a
`ja` here means the host Python, the host filesystem and `~/jobbsok-workspace`
are all reachable from Cowork -- which is what decision 7 is built on.

### F. Record and verify

Edit the four bullets under "Results" above, replacing `ubesvart`, and fill in
the Measured column with today's date. Then, from the repository root:

```bash
test "$(grep -cE '^- (Sesjonsmodus|Host-MCP|python3|CLAUDE_PLUGIN_ROOT): +(lokal VM|sky|ja|nei)\b' docs/cowork-probe.md)" = 4
```

Exit 0 means the probe is complete and plan Step 1 can be closed. Exit 1 means
at least one bullet is still unanswered or was written in a form the grep does
not recognise -- check that the answer follows the label directly, with a
space, and starts with one of the four allowed words.

## Degradation branch

Written now, so the answer does not get decided under pressure later.

**If `- Host-MCP:` is `nei`** — host-side stdio servers do not appear in this
Cowork installation:

1. Operator decision 7's Cowork half is unavailable. Nothing changes for Claude
   Code, where the scripts are invoked directly.
2. Every script-backed skill degrades to reading files that the Claude Code CLI
   produced. The skills stay useful; they stop being able to compute.
3. `Verifiser i Cowork` for the affected milestones means "the skills load and
   read files produced from Claude Code" — not "the connector answers".
4. The degradation is recorded in `STATE.md`.

This is risk H12's mitigation, and it is why the probe is the first step of the
build rather than a later check.

**If `- python3:` is `nei`** — a skill cannot invoke `python3` in a Cowork
session: the same degradation applies, and more broadly, since it removes the
CLI half too. Escalate to the operator before building further on decision 7.

**If `- CLAUDE_PLUGIN_ROOT:` is `nei`** — the variable does not resolve: every
intra-plugin path in the plan is affected, not just this milestone's. Escalate;
do not paper over it with hardcoded paths.

**If `- Sesjonsmodus:` is `sky`** — sessions run in the cloud, and host-side
servers cannot reach this machine at all. `- Host-MCP:` should then read `nei`,
and its branch applies. If the two disagree, the disagreement is the finding.