fix(route): don't let a splat catchall match paths sharing its prefix

[chuenchen309]

Problem

get_route_regex compiles the splat catchall to a bare .* with no separator in front of it, while every other segment type prepends /. So posts/[[...splat]] becomes ^/posts.*/?$, which matches any path that merely starts with the literal text:

>>> from reflex.route import get_router
>>> router = get_router(["posts/[[...splat]]"])
>>> router("/posts")            # 'posts/[[...splat]]'  — correct
>>> router("/postsomething")    # 'posts/[[...splat]]'  — wrong
>>> router("/posts-archive")    # 'posts/[[...splat]]'  — wrong

Why the second two are wrong

Not a judgement call — the frontend disagrees with it. _embed_manifest_path_for (packages/reflex-base/src/reflex_base/plugins/embed.py:42-73) maps [[...splat]] to React Router's *, so the same route compiles to posts/*, which matches /posts and its descendants but not /postsomething. The Python router and the router that actually renders the page were answering differently for the same path.

Impact

app.router feeds get_load_events (app.py:1038), called per page load from state.py:2467, and app.py:1804 (self.app.router(path) or "404"). A path resolving to the wrong route means a different page's on_load events fire than the page that renders.

Fix

.* → (/.*)?, making the separator required while keeping the zero-segment case (/posts itself) matching.

I probed the other segment types against React Router's semantics before changing anything — single, optional, and index all already agree, so the catchall was the only divergence.

Tests

test_get_router_splat_catchall in tests/units/test_route.py, parameterized over both the matching and non-matching cases. Verified red before the fix (the two prefix cases fail, the three legitimate ones pass), green after.

uv run pytest tests/units → 4340 passed. uv run ruff check . / ruff format --check clean, uv run pyright reflex tests → 0 errors. (tests/units/istate/manager/test_expiration.py is flaky on main independently of this change — it fails ~2 runs in 5 on a pristine checkout.)

AI assistance

Written with Claude Code. I verified the repro, the React Router mapping, and the pre-existing flake myself rather than taking them on the model's word, and I'm responsible for the contents.

[greptile-apps]

Greptile Summary

Fixes a regex mismatch in get_route_regex where [[...splat]] catchall routes compiled to .* (no separator), causing paths that merely shared the route's prefix (e.g. /postsomething) to incorrectly match posts/[[...splat]]. The Python router and the React Router frontend disagreed on these inputs, meaning the wrong page's on_load events could fire.

• reflex/route.py: Changes the DOUBLE_CATCHALL_SEGMENT regex fragment from .* to (/.*)?, requiring a / separator while keeping the zero-segment base path (e.g. /posts itself) matching — aligning with React Router's posts/* semantics.
• tests/units/test_route.py: Adds a parameterized test test_get_router_splat_catchall that covers the base path, a trailing-slash variant, a multi-segment descendant, and the two formerly-wrong prefix-only non-matching cases.

Confidence Score: 5/5

Safe to merge — the change is a single targeted regex fix backed by a focused, parameterized test suite that was verified red-before/green-after.

The fix is minimal (one regex fragment), correct against both the Python fullmatch call and React Router's posts/* semantics, and the added tests exercise all the important cases including the two paths that previously matched incorrectly. No other call sites are affected and no pre-existing functionality is disturbed.

No files require special attention.

Important Files Changed

Filename	Overview
reflex/route.py	Single-line fix in get_route_regex: .* → (/.*)? for DOUBLE_CATCHALL_SEGMENT, correctly requiring a / separator and making the capture optional for the base path; comment added explains the React Router alignment.
tests/units/test_route.py	Adds parameterized test_get_router_splat_catchall covering the base path, trailing-slash variant, a multi-segment descendant, and the two prefix-only non-matching cases that exposed the bug.
news/6790.bugfix.md	Changelog entry accurately describes the bug and its impact on on_load event routing.

_{Reviews (1): Last reviewed commit: "Add changelog fragment for #6790" | Re-trigger Greptile}