shell: document which edits are live and block patch 0008

deploy.sh: name the hazard the composer already implements — a new file
plus a manifest line is inert until the next deploy, while editing a file
already in the manifest is live in the running shell immediately.
Registration is the dangerous act, not creation.

patches/README: 0008 swaps the message delegate to one that does not carry
the vendor control row (regenerate, speak, re-synthesize, copy, edit, raw,
delete). Applying it would remove all seven.

surfaces/quickshell/deploy.sh

@@ -32,6 +32,29 @@ II="${QS}/ii"
 SV="${QS}/souveraine"
 TARGET_ARCH="${SOUVERAINE_TARGET_ARCH:-$(uname -m)}"
 
+# ── Which edits are live, and which are inert ────────────────────────────
+# Our manifest entries are composed as SYMLINKS into this repo, so the repo IS
+# the running shell for every file listed below. quickshell reloads on write.
+# The consequence, and it is the thing to know before touching anything here:
+#
+#   - Adding a NEW file + its MANIFEST line is INERT. The composed tree gains
+#     nothing until the next deploy.sh run. Build whole modules this way.
+#   - Editing a file ALREADY in the manifest is LIVE, immediately, in the
+#     running shell — no deploy needed, no confirmation, no undo.
+#
+# So registration is the dangerous act, not creation. A QML file that fails to
+# compile takes its whole module with it (a QtObject root with no default
+# property failed all of qs.services once, 29ec9fe), and quickshell will not
+# restart a config that crashes within 10s of launch — the bar simply stays
+# gone. Restarting the shell also re-locks the session via PAM, so it costs
+# the human a password.
+#
+# Practice: write patches into surfaces/quickshell/patches/ and let the human
+# apply and reload on their own beat; edit in a detached git worktree, never in
+# this tree. TASK-72's AgentPaneHost makes this structural — a candidate pane
+# loads beside the active one and only swaps on its ready signal — after which
+# a bad edit leaves the working pane drawn instead of taking the surface down.
+#
 # Manifest: "<repo-relative> <target-relative-to-~/.config/quickshell>"
 MANIFEST="
 shell.qml                    souveraine/shell.qml