Release v0.51.276 — Release IR (stage-p3e — preserve manually-named session titles #3542) (#3682)

* feat(sessions): skip adaptive auto-rename for manually-named sessions (#3542, #3230)

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>

* docs(changelog): v0.51.276 — Release IR (stage-p3e)

* fix(sessions): clear manual_title lock on /api/session/clear (#3542)

Codex regression-gate follow-up: the clear endpoint reset the title to
Untitled directly, stranding manual_title=True so the reused session never
auto-named again. Route the reset through apply_session_title_rename (which
clears the lock for auto-labels) + add a behavioral and a static-guard test.

---------

Co-authored-by: nesquena-hermes <[email protected]>
Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>

api/models.py

@@ -572,6 +572,7 @@ class Session:
                  truncation_watermark=None,
                  gateway_routing=None, gateway_routing_history=None,
                  llm_title_generated: bool=False,
+                 manual_title: bool=False,
                 parent_session_id: str=None,
                 worktree_path=None,
                 worktree_branch=None,
@@ -620,6 +621,7 @@ class Session:
         self.gateway_routing = gateway_routing if isinstance(gateway_routing, dict) else None
         self.gateway_routing_history = gateway_routing_history if isinstance(gateway_routing_history, list) else []
         self.llm_title_generated = bool(llm_title_generated)
+        self.manual_title = bool(manual_title)
         self.parent_session_id = parent_session_id
         self.worktree_path = str(Path(worktree_path).expanduser().resolve()) if worktree_path else None
         self.worktree_branch = str(worktree_branch) if worktree_branch else None
@@ -684,7 +686,7 @@ class Session:
             'compression_anchor_details', 'context_engine_state',
             'context_length', 'threshold_tokens', 'last_prompt_tokens',
             'truncation_watermark',
-            'gateway_routing', 'gateway_routing_history', 'llm_title_generated',
+            'gateway_routing', 'gateway_routing_history', 'llm_title_generated', 'manual_title',
             'parent_session_id',
             'worktree_path', 'worktree_branch', 'worktree_repo_root', 'worktree_created_at',
             'is_cli_session', 'source_tag', 'raw_source', 'session_source', 'source_label', 'read_only',
@@ -890,6 +892,7 @@ class Session:
             'last_prompt_tokens': self.last_prompt_tokens,
             'gateway_routing': self.gateway_routing,
             'gateway_routing_history': self.gateway_routing_history,
+            'manual_title': self.manual_title,
             # Only emit 'parent_session_id' when set (the /branch fork link, #1342).
             # Sessions without a fork must not leak None — see test_session_lineage_metadata_api.
             **({'parent_session_id': self.parent_session_id} if self.parent_session_id else {}),