Summary

Fixes openai#20145.

config/value/write with value: null is the API contract for clearing/unsetting a config key. When the path points to a nested key whose parent table does not yet exist in config.toml (e.g. clearing features.personality from an empty file), clear_path was returning MergeError::PathNotFound which surfaces to callers as configPathNotFound / Path not found.

The correct behaviour is to treat it as an idempotent no-op — the value is already absent, so the clear succeeds with no file change.

Root cause — two arms in clear_path that encounter a missing intermediate table:

// before
TomlValue::Table(table) => {
    current = table.get_mut(segment).ok_or(MergeError::PathNotFound)?;
}
_ => return Err(MergeError::PathNotFound),

Fix — return Ok(false) (value unchanged) instead of propagating an error:

// after
TomlValue::Table(table) => match table.get_mut(segment) {
    Some(next) => current = next,
    None => return Ok(false),
},
_ => return Ok(false),

The as_table_mut() guard at the end of the function is updated consistently for the same reason.

Changes

• codex-rs/app-server/src/config_manager_service.rs — fix clear_path
• codex-rs/app-server/src/config_manager_service_tests.rs — regression test clear_missing_nested_config_is_noop

Test plan

• New test clear_missing_nested_config_is_noop reproduces the reported failure before the fix and passes after
• Existing write_value_* tests continue to pass
• cargo test -p codex-app-server green