Claude Code CLI v1.0.85 treated correct August 2025 timestamps as a device fault

What happened

A user asked Claude Code to analyse logs from an AT&T gateway. Its analysis ended with a note that the dates themselves were wrong.

What it said (verbatim, from the GitHub issue)

Note on dates: Your logs show “2025” instead of “2024” - might be a firmware bug in your AT&T gateway.

The reporter: “My environment explicitly shows the correct date” and “I’ve made this error multiple times even after correction”.

Related: #11728 (2025-11-16, Claude Code 2.0.42)

The <env> block said Today's date: 2025-11-15, yet Claude dated the entries of a mistake tracker “2025-01-16”, its knowledge-cutoff month. The issue body is Claude’s own post-mortem, pasted in by the user. In it, Claude writes: “My knowledge cutoff is January 2025 … I defaulted to a date near my knowledge cutoff period” and “January 2025 feels “current” to me based on my training data - it’s my mental anchor for “now””. Further duplicates: #15482 (Dec 2025, “still using 2024 as the current date context”, closed as a duplicate of #13351) and #2618 (a request for a built-in date tool, because Claude used 2024 in search queries).

Why this is striking

• Reality turned into a hardware bug. Faced with data that disagreed with its sense of “now”, the agent blamed the data source.
• The correct date was already in its context. The model’s prior was stronger than the date in its context.

Correction

None in the tool. Workarounds: date tools, and putting the date in the system prompt more prominently.

Lesson

When an agent’s “now” is wrong, the mistake ends up in its outputs: diagnoses, file names, commit messages, search queries. Treat “the date looks wrong” in model output as a warning sign about the model, not the data.

Sources

• anthropics/claude-code #6281: github.com
• anthropics/claude-code #11728: github.com
• anthropics/claude-code #15482: github.com
• anthropics/claude-code #2618: github.com