CAST v1.5.0

Agents now inherit the session model instead of pinning Opus.

Changed

• All 15 agent frontmatter pins replaced with model: inherit. Agents run on whatever model the invoking session uses instead of being hard-pinned to claude-opus-4-8. The Claude Opus 4.x family remains the optimized target (claude-opus-4-8 recommended; claude-opus-4-7 and claude-opus-4-6 supported executing models), and role differentiation still comes from recommended reasoning effort. Explicit per-agent pins remain supported as user overrides.
• Documentation updated to the inherit-by-default policy — root README.md (what-you-get list, Agents placeholder section, prerequisites), agents/README.md, the three pipeline skills' Model Compatibility sections and skills/README.md, docs/MODEL_OPTIMIZATION.md (intro, ladder status, Default Roster Assignment table, effort notes, upgrade paths, verification steps), docs/FIRST_RUN.md's model-access caveat, the adoption skill's canonical structure description, and the roster reference (Model column and summary line). The four xhigh agents' effort notes now say "when the executing model is Opus 4.6" rather than "when pinned".
• Phase 6 validation (check 5) now accepts inherit as the default frontmatter model, with explicit pins (model aliases or full IDs) treated as user-approved overrides.

Added

• Model right-sizing at install time. The README, agents/README.md, references/roster.md, and docs/MODEL_OPTIMIZATION.md now recommend matching each agent's model to its workload to cost-optimize the roster — the most capable model (e.g. opus, or a Fable/Mythos-class model) on the judgment-heavy gates (CEO, Architect, Reviewer, Security), sonnet on the planning-and-implementation loop (Product, UI, Performance, Coder, Tester, Debugger, Refactor), and haiku on the utility roles (Bug Gatherer, Docs Writer, Release, Validator). /cast-init Phase 3 plans now include an Ask item proposing this assignment, and execution step 5.4 applies accepted pins to agent frontmatter during install.

Migration

• Existing installs: in each .claude/agents/*.md, change the frontmatter model: line to inherit (or keep an explicit pin if you rely on one for reproducibility or model-access reasons). Re-running /cast-init after updating applies this automatically.