0.5.3

• context-md check.sh: --base with no value no longer loops forever. A missing or empty value, or another option in its place, is a usage error (exit 2). (#15)
• context-md check.sh: a --base that git can't compare with no longer passes silently. An unknown ref, or a ref with no shared history such as a shallow clone's, now exits 2 with the reason, with or without --strict. --hook stays quiet and exits 0. CI that runs the check on a shallow checkout starts failing here, where it used to check nothing: check out with fetch-depth: 0. (#15)
• diagrams skill: the Mermaid check creates its output folder first, because mmdc fails when the folder doesn't exist. (#15)
• session-retro stats.sh: the baseline counts only retros with both numbers. A - in the log used to count as a retro and could print - or a wrong median; it stays "no baseline" until 3 retros have numbers. (#15)
• implementation skill: removing, relaxing or bypassing an existing authentication or authorization check is now listed under "Stop and report". (#15)
• tester agent: it may change an existing test's expectations when the task says the requirement changed and the user agreed, like the other kit files. Otherwise it leaves the test and reports it. (#16)
• Context check: "Done means" in AGENTS.md, the implementation skill and the context-md skill now say to add --base origin/<default branch> when the work is already committed. Without it the check saw only uncommitted changes. The context-md skill's origin/main example is gone, and it shows how to find the default branch. (#16)
• task-plans skill and architect agent: a contract-only first step must keep the current code working, so it adds a new field as optional and keeps an old one until a later step removes it. A contract that can't change compatibly gets one step that changes the contract and every side together. The architect now asks for contract tests only when the profile is (external, teams), like the task-plans skill. (#16)