fix: scope ticket cache per-PR and fix Dynaconf list merge leaks in tests (#2383)

.pr_agent.toml

@@ -6,6 +6,7 @@
 [pr_reviewer]
 enable_review_labels_effort = true
 enable_auto_approval = true
+cache_tickets = true
 
 [github_app]
 pr_commands = [

pr_agent/mosaico/env_bridge.py

@@ -39,6 +39,12 @@ def apply_mosaico_env() -> None:
     if model_name:
         model = model_name if "/" in model_name else f"openai/{model_name}"
         settings.set("CONFIG.MODEL", model)
+        # Dynaconf merge_enabled=True appends list values instead of replacing;
+        # pop the leaf first so the subsequent .set() produces a fresh list.
+        # Use case-insensitive matching because Dynaconf can normalize key casing.
+        for _k in list(settings.CONFIG.keys()):
+            if _k.lower() == "fallback_models":
+                settings.CONFIG.pop(_k, None)
         settings.set("CONFIG.FALLBACK_MODELS", [])
         # MOSAICO models are not in pr-agent's built-in MAX_TOKENS table; declare a budget
         # so reviews don't fail with "not defined in MAX_TOKENS". Overridable via env.
@@ -68,6 +74,12 @@ def _register_langfuse_callback(settings) -> None:
         current = [c for c in (settings.get(key, []) or []) if c != LEGACY_LANGFUSE_CALLBACK]
         if LANGFUSE_CALLBACK_NAME not in current:
             current.append(LANGFUSE_CALLBACK_NAME)
+        # Dynaconf merge_enabled=True appends list values; pop the leaf first.
+        # Use case-insensitive matching because Dynaconf can normalize key casing.
+        leaf = key.split(".", 1)[-1]
+        for _k in list(settings.LITELLM.keys()):
+            if _k.lower() == leaf.lower():
+                settings.LITELLM.pop(_k, None)
         settings.set(key, current)
     settings.set("LITELLM.ENABLE_CALLBACKS", True)
     get_logger().info("MOSAICO: registered Langfuse litellm callback.")

pr_agent/settings/configuration.toml

@@ -84,6 +84,7 @@ require_security_review=true
 require_estimate_contribution_time_cost=false
 require_todo_scan=false
 require_ticket_analysis_review=true
+cache_tickets=true
 # general options
 publish_output_no_suggestions=true # Set to "false" if you only need the reviewer's remarks (not labels, not "security audit", etc.) and want to avoid noisy "No major issues detected" comments.
 persistent_comment=true

pr_agent/tools/pr_reviewer.py

@@ -1,5 +1,6 @@
 import copy
 import datetime
+import hashlib
 import traceback
 from collections import OrderedDict
 from functools import partial
@@ -96,7 +97,7 @@ def __init__(self, pr_url: str, is_answer: bool = False, is_auto: bool = False,
             "custom_labels": "",
             "enable_custom_labels": get_settings().config.enable_custom_labels,
             "is_ai_metadata":  get_settings().get("config.enable_ai_metadata", False),
-            "related_tickets": get_settings().get('related_tickets', []),
+            "related_tickets": self._load_related_tickets(),
             'duplicate_prompt_examples': get_settings().config.get('duplicate_prompt_examples', False),
             "date": datetime.datetime.now().strftime('%Y-%m-%d'),
         }
@@ -108,6 +109,22 @@ def __init__(self, pr_url: str, is_answer: bool = False, is_auto: bool = False,
             get_settings().pr_review_prompt.user
         )
 
+    def _load_related_tickets(self):
+        if not get_settings().get('pr_reviewer.cache_tickets', True):
+            return []
+        pr_url = getattr(self.git_provider, 'pr_url', None)
+        if pr_url:
+            cache_key = f'related_tickets_{hashlib.md5(pr_url.encode()).hexdigest()}'
+            from pr_agent.tools.ticket_pr_compliance_check import _tickets_cache, _TICKETS_CACHE_TTL
+            import time
+            cached = _tickets_cache.get(cache_key)
+            if cached is not None:
+                ts, tickets = cached
+                if time.time() - ts < _TICKETS_CACHE_TTL:
+                    return tickets
+                del _tickets_cache[cache_key]
+        return get_settings().get('related_tickets', [])
+
     def parse_incremental(self, args: List[str]):
         is_incremental = False
         if args and len(args) >= 1:

pr_agent/tools/ticket_pr_compliance_check.py

@@ -1,11 +1,18 @@
+import hashlib
 import re
+import time
 import traceback
 
 from pr_agent.config_loader import get_settings
 from pr_agent.git_providers import GithubProvider
 from pr_agent.git_providers import AzureDevopsProvider
 from pr_agent.log import get_logger
 
+# In-memory ticket cache with TTL to avoid unbounded Dynaconf key accumulation.
+# Keys: md5(pr_url), values: (timestamp, ticket_list)
+_tickets_cache: dict = {}
+_TICKETS_CACHE_TTL = 3600  # 1 hour
+
 # Compile the regex pattern once, outside the function
 GITHUB_TICKET_PATTERN = re.compile(
      r'(https://github[^/]+/[^/]+/[^/]+/issues/\d+)|(\b(\w+)/(\w+)#(\d+)\b)|(#\d+)'
@@ -244,7 +251,29 @@ async def extract_and_cache_pr_tickets(git_provider, vars):
     if not get_settings().get('pr_reviewer.require_ticket_analysis_review', False):
         return
 
-    related_tickets = get_settings().get('related_tickets', [])
+    pr_url = getattr(git_provider, 'pr_url', None)
+    if not pr_url:
+        get_logger().info("No PR URL available — cannot cache tickets per-PR")
+        related_tickets = []
+        use_cache = False
+    else:
+        use_cache = get_settings().get('pr_reviewer.cache_tickets', True)
+        cache_key = (
+            f'related_tickets_{hashlib.md5(pr_url.encode()).hexdigest()}'
+        )
+        if use_cache:
+            cached = _tickets_cache.get(cache_key)
+            if cached is not None:
+                ts, tickets = cached
+                if time.time() - ts < _TICKETS_CACHE_TTL:
+                    related_tickets = tickets
+                else:
+                    del _tickets_cache[cache_key]
+                    related_tickets = []
+            else:
+                related_tickets = []
+        else:
+            related_tickets = []
 
     if not related_tickets:
         tickets_content = await extract_tickets(git_provider)
@@ -261,8 +290,9 @@ async def extract_and_cache_pr_tickets(git_provider, vars):
             get_logger().info("Extracted tickets and sub-issues from PR description",
                               artifact={"tickets": related_tickets})
 
-            vars['related_tickets'] = related_tickets
-            get_settings().set('related_tickets', related_tickets)
+        vars['related_tickets'] = related_tickets
+        if use_cache:
+            _tickets_cache[cache_key] = (time.time(), related_tickets)
     else:
         get_logger().info("Using cached tickets", artifact={"tickets": related_tickets})
         vars['related_tickets'] = related_tickets

tests/unittest/_settings_helpers.py

@@ -53,10 +53,14 @@ def _remove_key(settings, key):
 
 
 def restore_settings(snapshot):
-    """Restore ``snapshot``; truly remove entries whose snapshot is SENTINEL."""
+    """Restore ``snapshot``; truly remove entries whose snapshot is SENTINEL.
+
+    Because ``merge_enabled=True`` causes ``settings.set()`` to *append* list
+    values rather than replace them, the key is always removed first via
+    ``_remove_key`` before setting the restored value.
+    """
     settings = get_settings()
     for key, value in snapshot.items():
-        if value is SENTINEL:
-            _remove_key(settings, key)
-        else:
+        _remove_key(settings, key)
+        if value is not SENTINEL:
             settings.set(key, value)

tests/unittest/test_ignore_repositories.py

@@ -4,6 +4,7 @@
 from pr_agent.servers.bitbucket_app import should_process_pr_logic as bitbucket_should_process_pr_logic
 from pr_agent.servers.github_app import should_process_pr_logic as github_should_process_pr_logic
 from pr_agent.servers.gitlab_webhook import should_process_pr_logic as gitlab_should_process_pr_logic
+from tests.unittest._settings_helpers import _remove_key
 
 
 def make_bitbucket_payload(full_name):
@@ -42,11 +43,15 @@ def make_gitlab_body(full_name):
 
 class TestIgnoreRepositories:
     def setup_method(self):
-        get_settings().set("CONFIG.IGNORE_REPOSITORIES", [])
+        settings = get_settings()
+        _remove_key(settings, "CONFIG.IGNORE_REPOSITORIES")
+        settings.set("CONFIG.IGNORE_REPOSITORIES", [])
 
     @pytest.mark.parametrize("provider_name, provider_func, body_func", PROVIDERS)
     def test_should_ignore_matching_repository(self, provider_name, provider_func, body_func):
-        get_settings().set("CONFIG.IGNORE_REPOSITORIES", ["org/repo-to-ignore"])
+        settings = get_settings()
+        _remove_key(settings, "CONFIG.IGNORE_REPOSITORIES")
+        settings.set("CONFIG.IGNORE_REPOSITORIES", ["org/repo-to-ignore"])
         body = {
             "pull_request": {},
             "repository": {"full_name": "org/repo-to-ignore"},
@@ -58,7 +63,9 @@ def test_should_ignore_matching_repository(self, provider_name, provider_func, b
 
     @pytest.mark.parametrize("provider_name, provider_func, body_func", PROVIDERS)
     def test_should_not_ignore_non_matching_repository(self, provider_name, provider_func, body_func):
-        get_settings().set("CONFIG.IGNORE_REPOSITORIES", ["org/repo-to-ignore"])
+        settings = get_settings()
+        _remove_key(settings, "CONFIG.IGNORE_REPOSITORIES")
+        settings.set("CONFIG.IGNORE_REPOSITORIES", ["org/repo-to-ignore"])
         body = {
             "pull_request": {},
             "repository": {"full_name": "org/other-repo"},

tests/unittest/test_mosaico_env_bridge.py

@@ -13,6 +13,7 @@
                                          langfuse_env_present)
 from pr_agent.mosaico.observability import (mosaico_log_context,
                                             parse_observability_metadata)
+from tests.unittest._settings_helpers import _remove_key
 
 _SNAPSHOT_KEYS = [
     "OPENAI.API_BASE",
@@ -41,10 +42,8 @@ def restore_settings():
     litellm_failure = litellm.failure_callback
     yield
     for k, v in snapshot.items():
-        if v is _SENTINEL:
-            # Key was absent before; best-effort reset to empty so the global is not polluted.
-            global_settings.set(k, [] if k.endswith("CALLBACK") or k == "CONFIG.FALLBACK_MODELS" else None)
-        else:
+        _remove_key(global_settings, k)
+        if v is not _SENTINEL:
             global_settings.set(k, v)
     litellm.success_callback = litellm_success
     litellm.failure_callback = litellm_failure

tests/unittest/test_retry_with_fallback_models.py

@@ -5,7 +5,7 @@
 from pr_agent.algo.pr_processing import retry_with_fallback_models
 from pr_agent.algo.utils import ModelType
 from pr_agent.config_loader import get_settings
-from tests.unittest._settings_helpers import SENTINEL, restore_settings, snapshot_settings
+from tests.unittest._settings_helpers import SENTINEL, restore_settings, snapshot_settings, _remove_key
 
 _TRACKED_KEYS = (
     "config.model",
@@ -28,10 +28,13 @@ def _restore_settings(snapshot):
 def test_primary_model_success_invoked_once_and_returns_value():
     snapshot = _snapshot_settings()
     try:
-        get_settings().set("config.model", "primary-model")
-        get_settings().set("config.fallback_models", ["fallback-1", "fallback-2"])
-        get_settings().set("openai.deployment_id", None)
-        get_settings().set("openai.fallback_deployments", [])
+        settings = get_settings()
+        _remove_key(settings, "config.fallback_models")
+        settings.set("config.model", "primary-model")
+        settings.set("config.fallback_models", ["fallback-1", "fallback-2"])
+        _remove_key(settings, "openai.fallback_deployments")
+        settings.set("openai.deployment_id", None)
+        settings.set("openai.fallback_deployments", [])
 
         calls = []
 
@@ -50,10 +53,13 @@ async def fake_f(model):
 def test_primary_fails_fallback_succeeds():
     snapshot = _snapshot_settings()
     try:
-        get_settings().set("config.model", "primary-model")
-        get_settings().set("config.fallback_models", ["fallback-1", "fallback-2"])
-        get_settings().set("openai.deployment_id", None)
-        get_settings().set("openai.fallback_deployments", [])
+        settings = get_settings()
+        _remove_key(settings, "config.fallback_models")
+        settings.set("config.model", "primary-model")
+        settings.set("config.fallback_models", ["fallback-1", "fallback-2"])
+        _remove_key(settings, "openai.fallback_deployments")
+        settings.set("openai.deployment_id", None)
+        settings.set("openai.fallback_deployments", [])
 
         calls = []
 
@@ -74,10 +80,13 @@ async def fake_f(model):
 def test_all_models_fail_raises_with_aggregate_message_and_cause():
     snapshot = _snapshot_settings()
     try:
-        get_settings().set("config.model", "primary-model")
-        get_settings().set("config.fallback_models", ["fallback-1"])
-        get_settings().set("openai.deployment_id", None)
-        get_settings().set("openai.fallback_deployments", [])
+        settings = get_settings()
+        _remove_key(settings, "config.fallback_models")
+        settings.set("config.model", "primary-model")
+        settings.set("config.fallback_models", ["fallback-1"])
+        _remove_key(settings, "openai.fallback_deployments")
+        settings.set("openai.deployment_id", None)
+        settings.set("openai.fallback_deployments", [])
 
         last_error = ValueError("last failure")
         attempted = []
@@ -102,10 +111,13 @@ async def fake_f(model):
 def test_deployment_id_updated_per_attempt():
     snapshot = _snapshot_settings()
     try:
-        get_settings().set("config.model", "primary-model")
-        get_settings().set("config.fallback_models", ["fallback-1", "fallback-2"])
-        get_settings().set("openai.deployment_id", "deployment-primary")
-        get_settings().set(
+        settings = get_settings()
+        _remove_key(settings, "config.fallback_models")
+        _remove_key(settings, "openai.fallback_deployments")
+        settings.set("config.model", "primary-model")
+        settings.set("config.fallback_models", ["fallback-1", "fallback-2"])
+        settings.set("openai.deployment_id", "deployment-primary")
+        settings.set(
             "openai.fallback_deployments",
             ["deployment-fb1", "deployment-fb2"],
         )
@@ -134,11 +146,14 @@ async def fake_f(model):
 def test_weak_model_type_uses_weak_setting_and_forwards_identifier():
     snapshot = _snapshot_settings()
     try:
-        get_settings().set("config.model", "regular-model")
-        get_settings().set("config.model_weak", "weak-model-id")
-        get_settings().set("config.fallback_models", [])
-        get_settings().set("openai.deployment_id", None)
-        get_settings().set("openai.fallback_deployments", [])
+        settings = get_settings()
+        _remove_key(settings, "config.fallback_models")
+        _remove_key(settings, "openai.fallback_deployments")
+        settings.set("config.model", "regular-model")
+        settings.set("config.model_weak", "weak-model-id")
+        settings.set("config.fallback_models", [])
+        settings.set("openai.deployment_id", None)
+        settings.set("openai.fallback_deployments", [])
 
         calls = []
 
@@ -159,11 +174,14 @@ async def fake_f(model):
 def test_reasoning_model_type_uses_reasoning_setting():
     snapshot = _snapshot_settings()
     try:
-        get_settings().set("config.model", "regular-model")
-        get_settings().set("config.model_reasoning", "reasoning-model-id")
-        get_settings().set("config.fallback_models", [])
-        get_settings().set("openai.deployment_id", None)
-        get_settings().set("openai.fallback_deployments", [])
+        settings = get_settings()
+        _remove_key(settings, "config.fallback_models")
+        _remove_key(settings, "openai.fallback_deployments")
+        settings.set("config.model", "regular-model")
+        settings.set("config.model_reasoning", "reasoning-model-id")
+        settings.set("config.fallback_models", [])
+        settings.set("openai.deployment_id", None)
+        settings.set("openai.fallback_deployments", [])
 
         calls = []