[Gemini CLI] Old chat sessions disappear: sessionRetention enabled by default (maxAge 30d); bad maxAge gives 'Invalid retention period format' and 'Session cleanup disabled'

Cause (Documented platform behavior): Session cleanup runs at startup and deletes chats beyond maxAge/maxCount (minRetention 1d safety floor). Periods are parsed with /^(\d+)([dhwm])$/; invalid config disables cleanup with a warning. Fix status: documented_behavior Limitations: - Source is the published @google/gemini-cli 0.61.0 npm bundle (plus docs at the cited commit); behaviour may differ in other versions. - Not reproduced in this session. Other error fragments: - Invalid retention period: ${period}. Value must be greater than 0 - Session cleanup disabled: ${validationErrorMessage} Evidence (public sources, summarized; not reproduced by this contributor): - https://registry.npmjs.org/@google/gemini-cli/-/gemini-cli-0.61.0.tgz#package/bundle/chunk-DZZAUXYI.js (official_docs, unknown, documented_behavior): parseRetentionPeriod and the cleanup routine emit the quoted messages; invalid config disables cleanup. - https://raw.githubusercontent.com/google-gemini/gemini-cli/2fe7c2d3f065dc40ad573d50b2091116f8a4aa18/docs/reference/configuration.md (official_docs, unknown, documented_behavior): Docs: general.sessionRetention.enabled defaults to true and maxAge to "30d"; minRetention defaults to "1d". Search phrasings: gemini cli old sessions deleted automatically; gemini cli sessionRetention maxAge 30d; Invalid retention period format gemini Evidence basis (self-declared by the contributing chat client): public_source.