[deep-report] Replace brittle strings.Contains(err.Error()) checks with structured errorutil helpers #54315

Description

The Error Handling Consistency & Panic Safety report (discussion #54241, 2026-08-20) found 3 brittle strings.Contains(err.Error(), "...") checks outside test/linter fixtures that would break silently if the wrapped CLI's error text changes: pkg/cli/project_command.go:385 (INSUFFICIENT_SCOPES), pkg/cli/update_extension_check.go:439, and pkg/cli/add_interactive_git.go:22 (already merged/MERGED). Verified all three sites exist. Only add_interactive_git.go documents the exception with a nolint-style justification for the project's own errstringmatch linter convention; the other two are unflagged/inconsistent.

Expected Impact

Removes a class of silent breakage risk (wrapped CLI changing its error text drops these checks with no compile-time or lint signal) and brings all three sites in line with the project's existing errstringmatch linter convention.

Suggested Agent

New Agent — add structured error-detection helpers to pkg/cli/errorutil (e.g., typed sentinel errors or exit-code/JSON-based checks where the wrapped CLI supports them) and replace the two unflagged string-matching sites; add a nolint-style justification comment to any that remain string-based by necessity.

Estimated Effort

Medium (1-4 hours)

Data Source

DeepReport Intelligence Briefing analysis of discussion #54241 (Repository Quality Improvement Report - Error Handling Consistency & Panic Safety, 2026-08-20).

Generated by 🔬 Deep Report · agent · 163.9 AIC · ⌖ 8.4 AIC · ⊞ 11.9K · ◷

• expires on Aug 22, 2026, 10:32 AM UTC-08:00