Reword the Molecule scenario comments

They were hard-wrapped at 80 characters, broke mid-parenthesis, and spent lines
restating what the code below them does.

Rewrapped at natural boundaries instead, with the narration dropped and only the
reasons, gotchas and surprises kept. Section dividers stay - they delineate long
plays rather than narrate them.

Comments only; no scenario behaviour changes.

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

molecule-shared/playbook-context.yml

@@ -3,21 +3,18 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 ---
-# The variables a role here reads from its surroundings rather than from its own
-# defaults. In a real run `matrix-base` and `group_vars/matrix_servers` provide
-# them; in a scenario they have to come from somewhere, and including
-# `matrix-base` itself does far more than a role scenario needs.
+# The variables a role reads from its surroundings rather than from its own defaults.
+# In a real run `matrix-base` and `group_vars/matrix_servers` provide them.
 #
 # Include from a scenario's prepare.yml, converge.yml and verify.yml:
 #
 #   vars_files:
 #     - "{{ lookup('env', 'MOLECULE_PROJECT_DIRECTORY') }}/../../../molecule-shared/playbook-context.yml"
 #
-# A scenario can override any of these in its own group_vars - that is the point
-# of testing a role with values it would not have chosen for itself.
+# Gotcha: `vars_files` outranks inventory `group_vars`, so a scenario cannot override these there.
 #
-# Keep this to variables that come from OUTSIDE the role under test. Anything the
-# role defines belongs in the scenario, not here.
+# Keep this to variables that come from OUTSIDE the role under test.
+# Anything the role defines itself belongs in the scenario.
 
 # --- Identity and paths (matrix-base) --------------------------------------
 
@@ -27,32 +24,26 @@ matrix_domain: molecule.local
 matrix_user_name: matrix
 matrix_group_name: matrix
 
-# Deliberately not 1000: the base images already have a user there, so a distinct
-# id is what proves a role used the one it was given rather than coinciding with
-# the image's own.
+# Deliberately not 1000: the base images already have a user there, so a distinct id
+# is what proves a role used the one it was given rather than coinciding with the image's own.
 matrix_user_uid: 1234
 matrix_user_gid: 1234
 
-# Empty in the playbook's own defaults too. Components that would invite an
-# administrator into a room skip doing so when it is empty, which is what a
-# scenario wants.
+# Empty in the playbook's own defaults too. Components that would invite an administrator
+# into a room skip doing so when it is empty.
 matrix_admin: ''
 
 # --- Host commands (matrix-base) -------------------------------------------
-#
-# Some roles shell out to a host binary through this indirection instead of
-# naming it directly (matrix-bridge-hookshot and matrix-bridge-appservice-irc
-# both generate a key with it). matrix-base's defaults are what supplies the
-# value in a real run; those roles install the binary themselves, by including
-# matrix-base's `ensure_openssl_installed` tasks.
 
+# Some roles shell out through this indirection instead of naming the binary directly
+# (matrix-bridge-hookshot and matrix-bridge-appservice-irc both generate a key with it).
+# They install it themselves by including matrix-base's `ensure_openssl_installed` tasks.
 matrix_host_command_openssl: "/usr/bin/env openssl"
 
 # --- Bridge-wide switches (matrix-base) ------------------------------------
-#
-# Every bridge role reads these, so they live here rather than in each bridge's
-# scenario. The values match the playbook's own defaults: encryption off, no
-# relay, no MSC4190. A bridge scenario that wants to prove one of these reaches
+
+# Every bridge role reads these, so they live here rather than in each bridge's scenario.
+# The values match the playbook's own defaults. A scenario proving one of these reaches
 # the rendered configuration should override it in its own group_vars.
 
 matrix_bridges_encryption_enabled: false
@@ -66,10 +57,9 @@ matrix_bridges_exposure_hostname: molecule.local
 matrix_bridges_exposure_path_prefix: /bridges
 
 # --- Public hostnames (matrix-base) ----------------------------------------
-#
-# 18 of the roles here read one of these. Rendered against the scenario's
-# matrix_domain rather than left as Jinja, so a scenario can read them in
-# verify.yml without the role's defaults being in scope.
+
+# 18 of the roles here read one of these. Rendered against the scenario's matrix_domain
+# rather than left as Jinja, so verify.yml can read them without the role's defaults in scope.
 
 matrix_server_fqn_matrix: matrix.molecule.local
 matrix_server_fqn_matrix_federation: matrix.molecule.local