fix(memory): decouple shared tree id from legacy RALPH_PROJECT_ID (Addendum 4)

Runtime cross-feed bug: codex hooks export RALPH_PROJECT_ID=p-<hash> (session
id), which compute_project_id honored as an override -> codex wrote/read
memory_tree/projects/p-<hash>/ while claude used <remote>_<repo>/ -> separate
trees, no cross-feed despite identical schema/recall.

Fix: the shared tree id is keyed ONLY by git-remote-hash; the dedicated env var
RALPH_MEMORY_PROJECT_ID is the sole override. The legacy RALPH_PROJECT_ID is no
longer honored for the tree (it stays free for codex's ledger/handoff subsystem).

Verified (with RALPH_PROJECT_ID=p-legacy exported): both agents resolve the same
git-remote id; codex-written node read by claude recall and vice versa, single
physical tree dir. 111 tests; pyright 0/0. Mirror fix applied in
codex-ralph-vault-loop.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: alfredolopez80

scripts/memory/recall_v2.py

@@ -469,7 +469,7 @@ def main() -> int:
     parser.add_argument("--project-root", default=".")
     parser.add_argument("--query", default="")
     parser.add_argument("--json", action="store_true")
-    parser.add_argument("--project-id", default=os.environ.get("RALPH_PROJECT_ID", ""))
+    parser.add_argument("--project-id", default=os.environ.get("RALPH_MEMORY_PROJECT_ID", ""))
     parser.add_argument(
         "--ralph-home", default=os.environ.get("RALPH_HOME", "~/.ralph")
     )

scripts/memory/tree_store.py

@@ -184,13 +184,15 @@ def compute_project_id(repo_root: Path) -> str:
     memory tree (Addendum 2). Distinct repos still get distinct ids via the
     remote-hash and/or directory name.
 
-    ``RALPH_PROJECT_ID`` override (Wave 5, Addendum 3, 2026-06-17): if the env
-    var is set, it wins. This gives codex/claude an explicit escape hatch and
-    keeps compatibility with codex's existing ``RALPH_PROJECT_ID`` convention.
-    When unset, the git-remote-hash derivation below is used so the SAME target
-    repo yields the SAME id from either agent.
+    Tree-id override (Wave 5, Addendum 4, 2026-06-17): the DEDICATED env var
+    ``RALPH_MEMORY_PROJECT_ID`` wins when set. We deliberately do NOT honor the
+    legacy session var ``RALPH_PROJECT_ID`` here, because codex hooks set it to a
+    per-session ``p-<hash>`` id that would split the shared tree. The shared
+    memory tree is keyed by git-remote-hash so the SAME target repo yields the
+    SAME id from either agent; ``RALPH_PROJECT_ID`` stays free for codex's own
+    ledger/handoff subsystem.
     """
-    override = os.environ.get("RALPH_PROJECT_ID", "").strip()
+    override = os.environ.get("RALPH_MEMORY_PROJECT_ID", "").strip()
     if override:
         return safe_segment(override, "project_id")
     main_repo = resolve_main_repo_root(repo_root)