django.utils.http.parse_http_date two digit year check is incorrect

1. #1Problem statement pasteest. saving ~5,024 tokens · $0.0027

   What was sent

   django.utils.http.parse_http_date two digit year check is incorrect
   Description
   	 
   		(last modified by Ad Timmering)
   	 
   RFC 850 does not mention this, but in RFC 7231 (and there's something similar in RFC 2822), there's the following quote:
   Recipients of a timestamp value in rfc850-date format, which uses a
   two-digit year, MUST interpret a timestamp that appears to be more
   than 50 years in the future as representing the most recent year in
   the past that had the same last two digits.
   Current logic is hard coded to consider 0-69 to be in 2000-2069, and 70-99 to be 1970-1999, instead of comparing versus the current year.
   
   fix this

   How a strong engineer would ask

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   Task: django.utils.http.parse_http_date two digit year check is incorrect.

   In my words: ⟨restate this in one sentence: "Description (last modified by Ad Timmering) RFC 850 does not mention this, but in RFC 7231 (and there's something similar in RFC 2822), the…"⟩

   1. Read django/utils/http.py (django.utils.http.parse_http_date) and tell me where the current logic lives and which existing tests cover it. Don't edit yet.

   2. Propose the change in two or three lines, including how you'd handle the boundary cases.

   3. After I agree: implement it, add a regression test, and run the related tests.

   Constraints: ⟨what must not change, e.g. public API, existing tests⟩.

   Why it works. The issue text gives the agent the problem but not your plan, so it explores widely and commits to its first guess. Breaking it into read, propose, implement keeps each turn small and lets you reject a wrong approach before it is written, instead of steering after it is in the code.

   + the requirement in your words+ a read-first step+ a proposal before any edit+ constraints

   This turn used 33k tokens; the round's median turn used 38k. Trimming the paste would also have kept ~5,024 tokens of context off the 33 requests that followed.

2. #3Raw error pasteest. saving ~2,725 tokens · $0.0014

   What was sent

   Traceback (most recent call last):
     File "/workspace/repo/tests/utils_tests/test_http.py", line 7, in <module>
       from django.test import SimpleTestCase, ignore_warnings
     File "/workspace/repo/django/test/__init__.py", line 3, in <module>
       from django.test.client import Client, RequestFactory
     File "/workspace/repo/django/test/client.py", line 14, in <module>
       from django.core.handlers.base import BaseHandler
     File "/workspace/repo/django/core/handlers/base.py", line 8, in <module>
       from django.urls import get_resolver, set_urlconf
     File "/workspace/repo/django/conf/__init__.py", line 61, in _setup
       raise ImproperlyConfigured(
   django.core.exceptions.ImproperlyConfigured: Requested setting DEBUG, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.
   ERROR: tests/utils_tests/test_http.py - django.core.exceptions.ImproperlyConfigured

   How a strong engineer would ask

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   I ran tests/runtests.py utils_tests.test_http after your change to django/utils/http.py and expected tests/utils_tests/test_http.py to pass. It fails with ImproperlyConfigured, trimmed to the lines that matter:

   File "tests/utils_tests/test_http.py", line 7, in <module>
   File "django/core/handlers/base.py", line 8, in <module>
   from django.urls import get_resolver, set_urlconf
   File "django/conf/__init__.py", line 61, in _setup
   raise ImproperlyConfigured(
   django.core.exceptions.ImproperlyConfigured: Requested setting DEBUG, but settings are not configured. You must either define the environment variable DJANGO_S…

   It is raised in _setup (django/conf/__init__.py:61). My hypothesis: the tests ran without the project's settings, so the command is wrong rather than the code.

   Confirm or rule that out first, then make the smallest change that fixes it and re-run only tests/utils_tests/test_http.py.

   Why it works. A bare traceback tells the agent something broke but not what you were doing or what you suspect, so it guesses: it re-reads files and retries the last fix. This one (ImproperlyConfigured) fails before any test runs, which points at the test command or setup, not the code; saying so stops the agent from "fixing" code that was never the problem. And the full paste stays in the conversation, so every later request pays for it again.

   + the command you ran+ what you expected+ 6 relevant lines, not the whole dump+ a hypothesis+ a narrow next step

   This turn used 15k tokens; the round's median turn used 38k. Trimming the paste would also have kept ~2,725 tokens of context off the 21 requests that followed.

3. #4Low-effort nudgeest. saving ~8,619 tokens · $0.0046

   What was sent

   still failing, fix it

   How a strong engineer would ask

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   The last run still fails: 51 passed, 1 failed, after your change to django/utils/http.py.

   Before editing again, quote the failing assertion or error and explain in two sentences why it still fails.

   If the cause is outside django/utils/http.py (setup, imports, the test command), say so.

   Then propose one different approach and wait for my OK.

   Why it works. "still failing, fix it" adds no new information, so the agent usually retries a variant of the same idea. Here the next run ended exactly as before (51 passed, 1 failed). Asking for a diagnosis first is the cheapest way out of a loop: one short answer instead of another round of edits and test runs.

   + the evidence (counts)+ a diagnosis step+ a ban on blind retries+ a checkpoint

   This turn used 23k tokens and left the tests no better than before, so nearly all of it bought nothing; the cheapest turn in this round cost 15k, about 8,619 less.

4. #5Low-effort nudgeest. saving ~23k tokens · $0.012

   What was sent

   fix it

   How a strong engineer would ask

   Copy template

   The last run still fails: 51 passed, 1 failed, after your change to django/utils/http.py.

   Before editing again, quote the failing assertion or error and explain in two sentences why it still fails.

   If the cause is outside django/utils/http.py (setup, imports, the test command), say so.

   Then propose one different approach and wait for my OK.

   Why it works. "fix it" adds no new information, so the agent usually retries a variant of the same idea. Here the next run ended exactly as before (51 passed, 1 failed). Asking for a diagnosis first is the cheapest way out of a loop: one short answer instead of another round of edits and test runs.

   + the evidence (counts)+ a diagnosis step+ a ban on blind retries+ a checkpoint

   This turn used 38k tokens and left the tests no better than before, so nearly all of it bought nothing; the cheapest turn in this round cost 15k, about 23k less.

5. #6Code dumpat or below the round median

   What was sent

   use this:
   ```python
           year = int(m.group('year'))
           if year < 100:
               current_year = datetime.datetime.utcnow().year
               current_century = current_year - (current_year % 100)
               if year - (current_year % 100) > 50:
                   # more than 50 years in the future: the previous century
                   year += current_century - 100
               else:
                   year += current_century
   ```

   How a strong engineer would ask

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   In django/utils/http.py, I want this behavior: ⟨one sentence: what this code must achieve, and the edge case it handles⟩

   Here is the approach I have in mind (9 lines). Check it against the existing tests and the boundary cases before applying it, and tell me if any of it is wrong.

   year = int(m.group('year'))
   if year < 100:
       current_year = datetime.datetime.utcnow().year
       current_century = current_year - (current_year % 100)
       if year - (current_year % 100) > 50:
           # more than 50 years in the future: the previous century
           year += current_century - 100
       else:
           year += current_century

   Keep everything else in the file unchanged. Done means the related tests pass and it still meets what I asked in #2; show me the diff.

   Why it works. Pasting code with "use this" turns the agent into a typist: it applies the snippet without knowing what it must achieve, so it cannot catch a mistake in it or adapt it to the surrounding code. Stating the intent and asking for a check gets the review you skipped, and keeps the decision (and the understanding) yours, which is what an interviewer will ask about.

   + the file and function+ the intent in your words+ a request to check it+ what done means

   This turn used 31k tokens; the round's median turn used 38k.

Rewrites are built by rules from each prompt's own text and what happened around it; the ⟨bracketed⟩ parts are what only the engineer could fill in. Savings are estimates: a turn's tokens above this round's median turn (38k), or above its cheapest turn when the turn left the tests failing as before; plus, for pastes, the context the trimmed text would no longer carry on each later request (about four characters per token).