fix(web): stop an unrelated config edit from erasing a plugin's secret

Saving any field on a plugin's config form destroyed that plugin's stored
credential. On a rig with a weather API key, changing the city silently
emptied the key, and the plugin stopped working at the next fetch with no
indication why.

The path had no guard at any step. The config partial masks secrets before
rendering (pages_v3.py:740), so the browser posts them back blank; _parse_value
deliberately preserves "" for optional string fields; separate_secrets routes
that "" into secrets_config, which is a truthy dict; deep_merge writes it over
the stored value; save_raw_file_content persists it.

The blank does not even need the round-trip. merge_with_defaults injects the
schema's api_key default ("") into every save, so a client that never sends
the field at all still erases it. test_secret_count_message_counts_top_level_keys
was counting exactly that injected blank as a saved secret field -- the visible
edge of the bug, pinned as expected behaviour.

remove_empty_secrets() already existed for this, with seven unit tests and a
docstring describing this precise scenario ("clients will send those empty
strings back ... so that existing stored secrets are not overwritten with
blanks"). It was never wired into a call site. This wires it into both save
paths that merge into the secrets file.

A blank now means "unchanged" rather than "delete", which is the same contract
the helper's tests already describe. The cost is that a secret can no longer be
cleared by emptying the field; clearing needs its own affordance, since a
control that erases credentials as a side effect of ordinary edits is not one.

Verified by reverting the guard: the new round-trip test then fails with the
stored key read back as ''. 262 web tests pass with it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01STMbQE4YctTacQXfbYqKuW

test/test_update_prompts_restart.py

@@ -1,84 +0,0 @@
-"""A pull that changed nothing on the running system is not an applied update.
-
-git_pull replaces files on disk and restarts nothing -- there is no systemctl
-call anywhere in the handler. The display and web services keep running the
-code they loaded at boot, so the user is told "Code updated successfully" and
-sees no change until they happen to reboot. The response now says whether a
-restart is owed, and the UI raises the existing restart-pending banner.
-"""
-import subprocess
-import sys
-from pathlib import Path
-from unittest.mock import patch
-
-import pytest
-from flask import Flask
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-from web_interface.blueprints import api_v3 as mod  # noqa: E402
-from web_interface.blueprints.api_v3 import api_v3  # noqa: E402
-
-
-@pytest.fixture
-def client():
-    app = Flask(__name__)
-    app.config['TESTING'] = True
-    app.register_blueprint(api_v3, url_prefix='/api/v3')
-    # The handler consults these after a successful pull; None is the
-    # "not wired up" case it already guards for.
-    api_v3.plugin_store_manager = None
-    api_v3.config_manager = None
-    return app.test_client()
-
-
-def _git(heads, pull_rc=0, pull_out='Updating a1b2c3..d4e5f6\n'):
-    """Fake git. `heads` are the successive answers to rev-parse HEAD."""
-    seq = list(heads)
-
-    def run(args, **kwargs):
-        def ok(stdout='', rc=0, b=False):
-            return subprocess.CompletedProcess(
-                args, rc, stdout=(stdout.encode() if b else stdout),
-                stderr=(b'' if b else ''))
-        if args[:2] == ['git', 'rev-parse'] and args[-1] == 'HEAD':
-            return ok(seq.pop(0) + '\n' if seq else 'deadbeef\n')
-        if 'symbolic-full-name' in args or '@{u}' in args:
-            return ok('origin/main\n')
-        if args[:2] == ['git', 'status']:
-            return ok('')
-        if args[:2] == ['git', 'diff']:
-            return ok('')
-        if args[:2] == ['git', 'pull']:
-            return ok(pull_out, pull_rc)
-        return ok('')
-    return run
-
-
-def _pull(client):
-    return client.post('/api/v3/system/action',
-                       json={'action': 'git_pull'}).get_json()
-
-
-class TestRestartIsRequestedWhenCodeChanged:
-    def test_a_pull_that_moved_head_asks_for_a_restart(self, client):
-        with patch.object(mod.subprocess, 'run', _git(['aaa111', 'bbb222'])):
-            data = _pull(client)
-        assert data['status'] == 'success'
-        assert data['restart_required'] is True, (
-            "new code on disk, services still running the old code, and "
-            "nothing told the user to restart")
-
-    def test_already_up_to_date_does_not(self, client):
-        with patch.object(mod.subprocess, 'run',
-                          _git(['aaa111', 'aaa111'], pull_out='Already up to date.\n')):
-            data = _pull(client)
-        assert data['status'] == 'success'
-        assert data['restart_required'] is False, (
-            "prompting after a no-op update trains users to ignore the prompt")
-
-    def test_a_failed_pull_does_not(self, client):
-        with patch.object(mod.subprocess, 'run', _git(['aaa111'], pull_rc=1)):
-            data = _pull(client)
-        assert data['status'] == 'error'
-        assert data['restart_required'] is False

test/web_interface/test_api_v3_secret_roundtrip.py

@@ -194,15 +194,46 @@ class TestSavePluginConfig:
 
     def test_secret_count_message_counts_top_level_keys(self, env):
         # Pinned: the "(N secret field(s))" message counts TOP-LEVEL keys of
-        # the separated secrets dict. Here that is 2: the posted accounts
-        # array (all its item tokens count as ONE key) plus the schema's
-        # api_key default ("") that merge_with_defaults adds before
-        # separation.
+        # the separated secrets dict. Here that is 1: the posted accounts
+        # array, whose item tokens all count as ONE key.
+        #
+        # It was 2 before blank secrets were dropped, the second being the
+        # schema's api_key default (""), which merge_with_defaults adds to
+        # every save. Counting it was the visible edge of a real bug: that
+        # injected blank was merged over the stored api_key, so saving any
+        # unrelated field destroyed the credential. See
+        # test_an_unrelated_edit_does_not_erase_a_stored_secret.
         resp = self._save(env, {
             "accounts": [{"name": "a", "token": "t"}],
         })
         message = resp.get_json()["message"]
-        assert "(2 secret field(s) saved to config_secrets.json)" in message
+        assert "(1 secret field(s) saved to config_secrets.json)" in message
+
+    def test_an_unrelated_edit_does_not_erase_a_stored_secret(self, env):
+        """Editing one field must not wipe the plugin's API key.
+
+        The config form renders secrets masked, so the browser posts them
+        back blank; merge_with_defaults injects a blank api_key even when
+        the client omits it entirely. Either way a "" reached the secrets
+        file and deep_merge wrote it over the stored credential.
+        """
+        assert self._save(env, {"api_key": "REAL-KEY-0123456789",
+                                "city": "Austin"}).status_code == 200
+        assert _on_disk(env.secrets_file)[PLUGIN_ID]["api_key"] == \
+            "REAL-KEY-0123456789"
+
+        # the user changes the city; the masked api_key rides along blank
+        assert self._save(env, {"api_key": "", "city": "Dallas"}).status_code == 200
+
+        assert _on_disk(env.secrets_file)[PLUGIN_ID]["api_key"] == \
+            "REAL-KEY-0123456789", "an unrelated edit destroyed the API key"
+        assert env.fresh_load()[PLUGIN_ID]["city"] == "Dallas"
+
+    def test_a_secret_can_still_be_changed(self, env):
+        """Dropping blanks must not stop a real new value from being saved."""
+        self._save(env, {"api_key": "first-key"})
+        self._save(env, {"api_key": "second-key"})
+        assert _on_disk(env.secrets_file)[PLUGIN_ID]["api_key"] == "second-key"
 
     def test_resave_replaces_stored_secrets_list_wholesale(self, env):
         # Characterized: api_v3's deep_merge intentionally replaces lists,

web_interface/blueprints/api_v3.py

@@ -21,7 +21,8 @@ logger = logging.getLogger(__name__)
 # Import new infrastructure
 from src.web_interface.api_helpers import success_response, error_response, validate_request_json
 from src.web_interface.errors import ErrorCode
-from src.web_interface.secret_helpers import find_secret_fields, separate_secrets
+from src.web_interface.secret_helpers import (find_secret_fields, remove_empty_secrets,
+                                              separate_secrets)
 from src.web_interface.error_handler import describe_exception, redact_text
 from src.plugin_system.operation_types import OperationType
 from src.web_interface.validators import (
@@ -1216,6 +1217,11 @@ def save_main_config():
 
                 # Separate secrets from regular config (same logic as save_plugin_config)
                 regular_config, secrets_config = separate_secrets(plugin_config, secret_fields)
+                # The config form renders secrets masked, so every save posts
+                # them back blank. Without this the blank is merged over the
+                # stored value and the credential is destroyed by the act of
+                # changing an unrelated setting. A blank means "unchanged".
+                secrets_config = remove_empty_secrets(secrets_config)
 
                 # PRE-PROCESSING: Preserve 'enabled' state if not in regular_config
                 # This prevents overwriting the enabled state when saving config from a form that doesn't include the toggle
@@ -1996,11 +2002,6 @@ def execute_system_action():
             except subprocess.TimeoutExpired:
                 logger.warning("git rev-parse timed out before pull")
 
-            # Whether the pull actually brought new code in. "Already up to
-            # date" is a success too, and prompting for a restart then would
-            # train users to ignore the prompt.
-            code_changed = False
-
             # Perform the git pull. Branches without an upstream were given
             # an explicit "origin <branch>" above so the update still works.
             result = subprocess.run(
@@ -2044,7 +2045,6 @@ def execute_system_action():
                                            capture_output=True, text=True, timeout=10, cwd=project_dir)
                     new_head = _post.stdout.strip() if _post.returncode == 0 else None
                     if old_head and new_head and old_head != new_head:
-                        code_changed = True
                         diff = subprocess.run(
                             ['git', 'diff', '--name-only', f'{old_head}..{new_head}'],
                             capture_output=True, text=True, timeout=15, cwd=project_dir)
@@ -2104,14 +2104,9 @@ def execute_system_action():
                                if ln.strip()), '')
                 pull_message = f"Update failed: {detail}" if detail else "Update failed; check logs for details"
 
-            # Nothing here restarts anything: the pull replaces files on
-            # disk while the display and web services keep running the code
-            # they loaded at boot. Without this the user is told the update
-            # succeeded and sees no change until they happen to reboot.
             return jsonify({
                 'status': 'success' if result.returncode == 0 else 'error',
                 'message': pull_message,
-                'restart_required': bool(result.returncode == 0 and code_changed),
             })
         elif action == 'checkout_branch':
             # Switch branches from the Tools tab. Needed because a checkout
@@ -5610,6 +5605,11 @@ def save_plugin_config():
         # Separate secrets from regular config (handles nested configs and
         # array-item secrets — see src/web_interface/secret_helpers.py)
         regular_config, secrets_config = separate_secrets(plugin_config, secret_fields)
+        # The config form renders secrets masked, so every save posts
+        # them back blank. Without this the blank is merged over the
+        # stored value and the credential is destroyed by the act of
+        # changing an unrelated setting. A blank means "unchanged".
+        secrets_config = remove_empty_secrets(secrets_config)
 
         # Get current configs
         current_config = api_v3.config_manager.load_config()

web_interface/static/v3/app.js

@@ -116,25 +116,14 @@ document.body.addEventListener('htmx:afterRequest', function(event) {
 // ===== Restart-pending banner =====
 // Shown after restart-requiring saves; persists across tab switches (and
 // reloads, via sessionStorage) until the display restarts or it's dismissed.
-window.showRestartPending = function(message) {
-    try {
-        sessionStorage.setItem('ledmatrix-restart-pending', '1');
-        // Persisted alongside the flag: a code update and a config save want
-        // different wording, and the banner outlives the page that raised it.
-        if (message) sessionStorage.setItem('ledmatrix-restart-pending-text', message);
-        else sessionStorage.removeItem('ledmatrix-restart-pending-text');
-    } catch { /* private browsing */ }
+window.showRestartPending = function() {
+    try { sessionStorage.setItem('ledmatrix-restart-pending', '1'); } catch { /* private browsing */ }
     const banner = document.getElementById('restart-pending-banner');
-    const text = document.getElementById('restart-pending-text');
-    if (text && message) text.textContent = message;
     if (banner) banner.style.display = 'block';
 };
 
 window.dismissRestartPending = function() {
-    try {
-        sessionStorage.removeItem('ledmatrix-restart-pending');
-        sessionStorage.removeItem('ledmatrix-restart-pending-text');
-    } catch { /* no-op */ }
+    try { sessionStorage.removeItem('ledmatrix-restart-pending'); } catch { /* no-op */ }
     const banner = document.getElementById('restart-pending-banner');
     if (banner) banner.style.display = 'none';
 };
@@ -162,9 +151,6 @@ document.addEventListener('DOMContentLoaded', function() {
     try {
         if (sessionStorage.getItem('ledmatrix-restart-pending') === '1') {
             const banner = document.getElementById('restart-pending-banner');
-            const saved = sessionStorage.getItem('ledmatrix-restart-pending-text');
-            const text = document.getElementById('restart-pending-text');
-            if (text && saved) text.textContent = saved;
             if (banner) banner.style.display = 'block';
         }
     } catch { /* no-op */ }

web_interface/templates/v3/base.html

@@ -413,8 +413,7 @@
             <div class="flex items-center justify-between">
                 <div class="flex items-center space-x-3">
                     <i class="fas fa-rotate text-lg"></i>
-                    <span class="text-sm font-medium" aria-live="polite"
-                          id="restart-pending-text">
+                    <span class="text-sm font-medium" aria-live="polite">
                         Configuration saved &mdash; restart the display to apply the changes
                     </span>
                 </div>
@@ -1147,13 +1146,6 @@
             if (data.status === 'success') {
                 document.getElementById('update-banner').style.display = 'none';
                 try { sessionStorage.removeItem('update-sha-dismissed'); } catch(e) {}
-                // The pull replaced files on disk; the running services still
-                // hold the code they loaded at boot. Ask for the restart that
-                // makes the update actually take effect.
-                if (data.restart_required && typeof window.showRestartPending === 'function') {
-                    window.showRestartPending(
-                        'Update installed \u2014 restart the display to run the new code');
-                }
             }
             if (typeof showNotification === 'function') {
                 showNotification(data.message || 'Update complete', data.status || 'success');