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

A bot rather than a bridge, and not an appservice: it logs into the
homeserver as an ordinary user with a password, and keeps its reminders in
a local SQLite database. That makes it a cheap second data point for the
bot shape, and it is closer to matrix-alertmanager-receiver than to the
bridges - except that it has no HTTP surface at all, so there is nothing to
probe.

What the scenario proves instead:

- The unit is active and has not restarted. The bot parses its config file
  before its own catch-all retry loop starts, so anything wrong in what the
  role rendered surfaces as a crash loop rather than as a running process.
- The bot reached "Logged in as @molecule.reminder-bot:molecule.local" in
  the journal. That line is only reached once the login call came back as
  something other than an error, so it covers the homeserver URL, the user
  ID and the password the role rendered in one go - a real login round-trip
  against the shared stub, which already answers /_matrix/client/v3/login
  with an access token. No stub changes were needed.
- The SQLite database landed at the path the role configured, owned by the
  role's uid, with the role's own default name (bot.db) absent as a negative
  control - so the storage configuration reached the running process and not
  just the file on disk.
- matrix-nio populated its encryption store under the role's data path,
  inside an otherwise read-only container.
- The container runs as the playbook context's uid:gid with the configured
  timezone on TZ, and carries the version defaults/main.yml pins.
- `..._configuration_extension_yaml` was merged over the role's template:
  device_name is hardcoded in the template, so overriding it is only
  possible through the extension.

Every value the scenario sets differs from both the role's defaults and the
bot's own fallbacks - localpart, command prefix, timezone, database
filename, both the allowlist and the blocklist.

Falsified by pointing the homeserver URL at a dead port. The service stayed
`active` with NRestarts == 0 and that assertion passed, because the bot
catches every exception and retries every 15s rather than exiting - a good
illustration of why `active` on its own proves nothing here. The run failed
at "Assert the bot logged in as the user the role configured", which is the
assertion carrying the weight.

Surprise worth recording: the journal is read through a grep rather than a
`--lines=N` tail. The startup lines are the oldest in the journal, and if
the stub ever answers /sync instantly the bot's sync loop spins fast enough
to bury them under thousands of lines within a minute.

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