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fix(CORE-355): handle abbreviated timezone offsets in convert_partial_iso_format_to_full_iso_format #2116

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Merged
haritamar merged 3 commits into from
Feb 18, 2026
Merged

fix(CORE-355): handle abbreviated timezone offsets in convert_partial_iso_format_to_full_iso_format #2116

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d86d3fe
fix(CORE-355): handle abbreviated timezone offsets in convert_partial…
devin-ai-integration[bot] Feb 17, 2026
b38a4b5
fix: tighten regex to require time component before abbreviated tz of…
devin-ai-integration[bot] Feb 17, 2026
c1dbe64
test: add parametrized tests for convert_partial_iso_format_to_full_i…
devin-ai-integration[bot] Feb 17, 2026
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14 changes: 11 additions & 3 deletions elementary/utils/time.py
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import re
from datetime import datetime, timedelta, timezone
from typing import Optional

Expand Down Expand Up @@ -89,17 +90,24 @@ def datetime_strftime(datetime: datetime, include_timezone: bool = False) -> str
)


_ABBREVIATED_TZ_OFFSET_PATTERN = re.compile(r"([+-])(\d{2})$")
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@devin-ai-integration devin-ai-integration Bot Feb 17, 2026

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🟡 Regex falsely matches date components (e.g., -15 in 2024-01-15) as abbreviated timezone offsets

The regex ([+-])(\d{2})$ is too broad and matches trailing -DD in date-only ISO strings, corrupting them before parsing.

Root Cause and Impact

The pattern _ABBREVIATED_TZ_OFFSET_PATTERN = re.compile(r"([+-])(\d{2})$") matches any string ending with +XX or -XX. This means a date-only string like "2024-01-15" matches on "-15" and gets rewritten to "2024-01-15:00".

Verified with the actual code:

"2024-01-15" → "2024-01-15:00"  (corrupted!)
"2024-12"    → "2024-12:00"     (corrupted!)

In the current Python 3.10 environment, datetime.fromisoformat("2024-01-15:00") happens to parse identically to datetime.fromisoformat("2024-01-15") (both yield 2024-01-15 00:00:00) because fromisoformat accepts any single character as a date-time separator. So the output is currently identical by coincidence, but this is fragile — it relies on a quirk of fromisoformat's separator handling.

A safer pattern would anchor to a time component before the offset, e.g.:

re.compile(r"(\d{2}:\d{2}(?::\d{2})?(?:\.\d+)?)([+-])(\d{2})$")

or at minimum require a T or digit before the +/-:

re.compile(r"(?<=\d)([+-])(\d{2})$")

Impact: Currently minimal because the coincidental parse behavior produces the same result, but the function silently corrupts its input for date-only strings. This could become a real issue with future Python version changes to fromisoformat parsing behavior, or with other partial ISO format inputs (like "2024-12").

Suggested change
_ABBREVIATED_TZ_OFFSET_PATTERN = re.compile(r"([+-])(\d{2})$")
_ABBREVIATED_TZ_OFFSET_PATTERN = re.compile(r"(?<=\d{2})([+-])(\d{2})$")
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@devin-ai-integration devin-ai-integration Bot Feb 17, 2026

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Good catch — the original ([+-])(\d{2})$ would indeed match -15 in date-only strings like 2024-01-15.

I've tightened the pattern to (:\d{2}(?:\.\d+)?)([+-])(\d{2})$ which requires a time component (:SS or :SS.fraction) before the +/-, so it only fires on actual timezone offsets after timestamps. Pushed in b38a4b5.



def _normalize_timezone_offset(time_string: str) -> str:
return _ABBREVIATED_TZ_OFFSET_PATTERN.sub(r"\1\2:00", time_string)


def convert_partial_iso_format_to_full_iso_format(partial_iso_format_time: str) -> str:
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try:
date = datetime.fromisoformat(partial_iso_format_time)
# Get the given date timezone
normalized = _normalize_timezone_offset(partial_iso_format_time)
date = datetime.fromisoformat(normalized)
time_zone_name = date.strftime("%Z")
time_zone = tz.gettz(time_zone_name) if time_zone_name else tz.UTC
date_with_timezone = date.replace(tzinfo=time_zone, microsecond=0)
return date_with_timezone.isoformat()
except ValueError:
logger.exception(
f'Failed to covert time string: "{partial_iso_format_time}" to ISO format'
f'Failed to convert time string: "{partial_iso_format_time}" to ISO format'
)
return partial_iso_format_time

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