A rejected JP_CFG_* value is reported without its reason

Todo2026-10-13jp

package: jp_clitype: bug

A JP_CFG_* variable whose value fails to parse stops the run with an error that says neither what is wrong nor which variable is at fault:

$ JP_CFG_STYLE_REASONING_WINDOW_ROWS=loads jp config show >/dev/null
CLI Config error
| error | style_reasoning_window_rows: parse error |

The same value given with --cfg names the values that are accepted:

$ jp config show -c style.reasoning.window.rows=loads
CLI Config error

 error  style.reasoning.window.rows: parse error: invalid row count `loads`: expected `off`, `auto`, `false`, `true`, or a number of rows

It is not specific to this key. A value rejected by its key's own parser becomes a KvAssignmentErrorKind::Parse error (assignment_error in crates/jp_config/src/assignment.rs), which displays as parse error and carries the reason as its source.

Cause

load_base_partial (crates/jp_cli/src/lib.rs:1022) and load_user_global_partial (crates/jp_cli/src/lib.rs:1031) turn the load_envs error into Error::CliConfig(error.to_string()), which keeps the outer message and drops the source.

The --cfg path (crates/jp_cli/src/config_pipeline.rs:539) formats the same error with crate::error::error_chain, which appends each source.

The key in the message is the variable's name lowercased, with JP_CFG_ stripped (style_reasoning_window_rows), so it matches neither the variable that was set nor the config key.

Fix

Format both call sites with error_chain, as the --cfg path does, and name the variable as it was set:

JP_CFG_STYLE_REASONING_WINDOW_ROWS: parse error: invalid row count `loads`: expected `off`, `auto`, `false`, `true`, or a number of rows

Pin the message in a test that sets the variable.

Context

Found while checking the config surface of RFD 120 (T-0z7cwrr).