Increase default stop arrival fetch count

[rsun19]

Summary

• Increased the default value for stop arrival search results (DEFAULT_STOP_SEARCH_LIMIT) to 30, allowing more arrivals to be fetched per request.
• Updated backend logic to use the new default where applicable.
• Improves user experience by displaying more upcoming arrivals at once, reducing the need for additional fetches.

---

Technical details:

• Changed the DEFAULT_STOP_SEARCH_LIMIT constant in the backend.
• All endpoints and services using this constant now return up to 30 arrivals by default.

Why:

• Users requested to see more arrivals per stop without extra clicks or requests.
• This change optimizes the display of transportation arrival information and reduces API round-trips.

Testing:

• Verified that stop arrival endpoints now return up to 30 results by default.
• Confirmed no regressions in pagination or limit enforcement.

---

Closes #30 if applicable.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a new constant DEFAULT_STOP_SEARCH_LIMIT set to 30 and updates the getArrivals() method in StopsService to use this new constant as its default limit parameter instead of the generic DEFAULT_SEARCH_LIMIT.

Changes

Cohort / File(s)	Summary
Constants Definition backend/src/common/constants.ts	Adds new exported constant DEFAULT_STOP_SEARCH_LIMIT with value 30 for stop-specific search result pagination.
Service Parameter Update backend/src/modules/stops/stops.service.ts	Updates getArrivals() method default parameter from DEFAULT_SEARCH_LIMIT to DEFAULT_STOP_SEARCH_LIMIT, changing the default page size for stop arrival queries.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Poem

🐰 A stop search limit, oh what a treat!
Thirty arrivals, a tidy retreat.
Constants defined, parameters refined,
Better defaults for searches aligned! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Title check	✅ Passed	The title accurately describes the main change: introducing a new constant to increase the default limit for stop arrival fetches from the default search limit to 30.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch add-more-fetching

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

backend/src/modules/stops/stops.service.ts (1)

184-188: ⚠️ Potential issue | 🟠 Major

Normalize limit before building the cache key.

Line [187] keys by raw limit, but Line [328] caps it. This can fragment cache entries and waste Redis memory for identical result sets.

Proposed fix

   async getArrivals(
     stopId: string,
     agencyKey: string,
     limit = DEFAULT_STOP_SEARCH_LIMIT,
     after?: string,
   ): Promise<{ data: ArrivalResponse[]; stopId: string; agencyKey: string; stopName: string }> {
-    const cacheKey = `cache:arrivals:v3:${agencyKey}:${stopId}:${limit}:${after ?? 'now'}`;
+    const cappedLimit = Math.min(limit, MAX_SEARCH_LIMIT);
+    const cacheKey = `cache:arrivals:v3:${agencyKey}:${stopId}:${cappedLimit}:${after ?? 'now'}`;
@@
-        Math.min(limit, MAX_SEARCH_LIMIT),
+        cappedLimit,
       ],
     );

Also applies to: 328-329

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@backend/src/modules/stops/stops.service.ts` around lines 184 - 188, Normalize
the incoming limit before building cacheKey to avoid fragmented Redis entries:
compute a normalizedLimit using the same capping logic applied later (e.g.,
normalizedLimit = Math.min(limit, DEFAULT_STOP_SEARCH_LIMIT) or call the
existing cap used around lines 328-329), then use normalizedLimit (not raw
limit) when creating cacheKey
(`cache:arrivals:v3:${agencyKey}:${stopId}:${normalizedLimit}:${after ??
'now'}`) so cache keys match the actual query size used by the rest of the
function.

🧹 Nitpick comments (1)

backend/src/common/constants.ts (1)

36-36: Clarify constant intent to avoid misuse.

DEFAULT_STOP_SEARCH_LIMIT is easy to confuse with the existing search-page default. Consider renaming it to an arrivals-specific name (or add a clear comment) so future call sites don’t apply it to the wrong endpoint.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@backend/src/common/constants.ts` at line 36, The constant
DEFAULT_STOP_SEARCH_LIMIT is ambiguous and may be misused; rename it to
something arrivals-specific (e.g., ARRIVALS_DEFAULT_SEARCH_LIMIT) or add a clear
inline comment above DEFAULT_STOP_SEARCH_LIMIT clarifying it's only for
arrivals/stop-arrivals endpoint; update all references/usages (imports, tests,
and any modules that consume DEFAULT_STOP_SEARCH_LIMIT) to the new name or rely
on the clarified comment so callers for the search-page default are not
accidentally using this value.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In `@backend/src/modules/stops/stops.service.ts`:
- Around line 184-188: Normalize the incoming limit before building cacheKey to
avoid fragmented Redis entries: compute a normalizedLimit using the same capping
logic applied later (e.g., normalizedLimit = Math.min(limit,
DEFAULT_STOP_SEARCH_LIMIT) or call the existing cap used around lines 328-329),
then use normalizedLimit (not raw limit) when creating cacheKey
(`cache:arrivals:v3:${agencyKey}:${stopId}:${normalizedLimit}:${after ??
'now'}`) so cache keys match the actual query size used by the rest of the
function.

---

Nitpick comments:
In `@backend/src/common/constants.ts`:
- Line 36: The constant DEFAULT_STOP_SEARCH_LIMIT is ambiguous and may be
misused; rename it to something arrivals-specific (e.g.,
ARRIVALS_DEFAULT_SEARCH_LIMIT) or add a clear inline comment above
DEFAULT_STOP_SEARCH_LIMIT clarifying it's only for arrivals/stop-arrivals
endpoint; update all references/usages (imports, tests, and any modules that
consume DEFAULT_STOP_SEARCH_LIMIT) to the new name or rely on the clarified
comment so callers for the search-page default are not accidentally using this
value.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fd547dec-b9e4-44ab-ba3e-b401e1cc46b8

📥 Commits

Reviewing files that changed from the base of the PR and between 0b44947 and a5f5caf.

📒 Files selected for processing (2)

• backend/src/common/constants.ts
• backend/src/modules/stops/stops.service.ts