Scenarios install their Galaxy dependencies with `force: true`, so two roles
running at once re-extract the same collections and roles into ~/.ansible and
pull them out from under each other mid-play. It surfaces as a collection that
was working moments earlier going missing:

  the connection plugin 'community.docker.docker' was not found

Found while running five scenarios in parallel, where it cost a run.

ANSIBLE_HOME relocates both `collections/` and `roles/`, so one variable covers
both halves; the scenarios' ANSIBLE_ROLES_PATH workaround now follows it rather
than hardcoding ~/.ansible/roles. Left alone if already set, and unset in CI,
where each role runs in its own job and has nothing to collide with.

Verified by removing var/molecule-ansible-home entirely and running
matrix-alertmanager-receiver from cold: green through idempotence, with the
collections and roles landing under the per-role directory - which also shows
nothing was quietly relying on the shared ~/.ansible being populated.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SEH3vxYSQ5SV4N5z61eyGT

Hookshot is the widest HTTP surface of the bridges here - an appservice port
plus a `listeners` list whose entries appear or vanish with independent
switches - so the scenario asserts on that surface rather than on "it started".

The scenario configures NO third-party service. GitHub, GitLab, Jira and Figma
each need an account and a credential somewhere else, which is where a scenario
stops testing this repository (docs/molecule-testing.md). GitLab, which the role
turns on by default, is switched off and its absence from both config.yml and
the registration's namespaces is asserted. The generic webhooks listener needs
no credential from anyone, and is what gets exercised live: a POST to an unknown
hook id comes back as `{"ok":false,"error":"Webhook not found"}`, which only
Hookshot's own generic-webhook handler produces - an Express "Cannot POST" page
there would mean the port is Hookshot's but the service was never mounted on it.

Every port the scenario sets differs from both the role's default and Hookshot's
own, and the run asserts both halves: the webhooks, metrics and appservice ports
it chose all answer, and 9000/9001/9003/9993 - what the role would have used
instead - all refuse. Metrics are off in the role's defaults, so that listener
exists only because the scenario asked for it, and /metrics answers with
`hookshot_*` series that nothing else could have produced.

config.yml and registration.yml are parsed as YAML and asserted structurally, so
a value landing under the wrong key cannot pass as a substring match.

Two things the role made necessary:

- `tasks/main.yml` opens with a block tagged `reset-hookshot-encryption`, and
  Ansible runs tagged tasks unless tags are actually selected - so any tagless
  play hits it, and it stops `matrix-hookshot.service` before that service
  exists. The scenario skips the tag, which is what the playbook effectively
  does by always running with `--tags=setup-all,start`.

- The role reads `matrix_host_command_openssl`, which matrix-base defines.
  matrix-bridge-appservice-irc reads it too, so it goes in the shared playbook
  context rather than into this scenario.

Falsified by pointing the webhooks listener at 127.0.0.1 in the role's config
template - a change no file-level assertion can see. Every config and
registration assertion still passed, and the run failed at "Assert the generic
webhooks service is mounted on that listener" with "Port 9741 did not answer as
Hookshot's generic webhooks service". Reverted afterwards.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SEH3vxYSQ5SV4N5z61eyGT