From 29583c55ed045af3675dd9de2b10de7c64a4ab4c Mon Sep 17 00:00:00 2001
From: Rudy Celekli <rudy@gradiahq.com>
Date: Wed, 14 Oct 2026 20:12:29 -0400
Subject: [PATCH] fix(firms): reject impossible acquisition days in CSV parsing

Rebased onto current main with review follow-ups folded in.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 CHANGELOG.md                              |  2 ++
 docs/CURRENT-STATE.md                     |  2 ++
 src/data/firms-calendar-validity.test.mjs | 23 +++++++++++++++++++++++
 src/data/firmsCsv.js                      |  8 +++++++-
 4 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 src/data/firms-calendar-validity.test.mjs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a770fbd35..ca4974a0c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -33,6 +33,8 @@
 
 - Director timeline seeks cross the dateline along the short longitude arc.
 
+- Reject impossible FIRMS acquisition calendar days in the CSV parser before trailing-24-hour filtering.
+
 - Treat explicitly current, complete empty vessel coverage as a successful update,
   clearing obsolete contacts while retaining stale or incomplete snapshots.
 
diff --git a/docs/CURRENT-STATE.md b/docs/CURRENT-STATE.md
index 1f794a5b5..6a4f3061b 100644
--- a/docs/CURRENT-STATE.md
+++ b/docs/CURRENT-STATE.md
@@ -1429,6 +1429,8 @@ accessible name remains "Don't show this again". Control behavior is unchanged.
 
 ## FIRMS source status
 
+The FIRMS CSV parser rejects impossible acquisition calendar dates before the proxy filters records to the trailing 24 hours, while retaining valid UTC acquisition times.
+
 The FIRMS proxy records source success after appending its rows. If aggregation
 throws, that source reports failure without a contradictory success entry.
 The existing per-record append continues to support large feeds; sequential
diff --git a/src/data/firms-calendar-validity.test.mjs b/src/data/firms-calendar-validity.test.mjs
new file mode 100644
index 000000000..1ccaf7435
--- /dev/null
+++ b/src/data/firms-calendar-validity.test.mjs
@@ -0,0 +1,23 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { acquisitionMsUtc } from './firmsCsv.js';
+test('FIRMS acquisition dates cannot roll into a different calendar day', () => {
+  for (const [date, time] of [
+    ['2026-02-30', '1200'],
+    ['2026-04-31', '1200'],
+    ['2026-13-01', '1200'],
+    ['2026-07-16junk', '1200'],
+    ['2026-07-16', '2400'],
+    ['2026-07-16', '1260'],
+    ['2026-07-16', null],
+    ['2026-07-16', ''],
+  ]) {
+    assert.ok(Number.isNaN(acquisitionMsUtc(date, time)), `${date}:${time}`);
+  }
+  for (const [date, time, expected] of [
+    ['2024-02-29', '45', Date.UTC(2024, 1, 29, 0, 45)],
+    ['2026-07-16', '0', Date.UTC(2026, 6, 16)],
+  ]) {
+    assert.equal(acquisitionMsUtc(date, time), expected);
+  }
+});
diff --git a/src/data/firmsCsv.js b/src/data/firmsCsv.js
index 7f9019e18..53d132d99 100644
--- a/src/data/firmsCsv.js
+++ b/src/data/firmsCsv.js
@@ -153,7 +153,13 @@ export function acquisitionMsUtc(acqDate, acqTime) {
     minutes > 59
   )
     return NaN;
-  return Date.UTC(year, month - 1, day, hours, minutes);
+  const ms = Date.UTC(year, month - 1, day, hours, minutes);
+  const parsed = new Date(ms);
+  return parsed.getUTCFullYear() === year &&
+    parsed.getUTCMonth() === month - 1 &&
+    parsed.getUTCDate() === day
+    ? ms
+    : NaN;
 }
 
 /**