Port two refinements from the GLM variant onto the Claude base:
- prepareAgentStep: add a comment note that AI SDK v7 renames the per-step
`system` field to `instructions` (v6 ^6.0.134 still uses `system`), so it
gets updated correctly on the next SDK bump.
- ai-chat.service.spec: add an explicit off-by-one boundary test for
prepareAgentStep, expressed via MAX_AGENT_STEPS instead of a hardcoded 18/19
so it tracks the constant if the cap changes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A narrow research question could burn all 8 steps on tool calls and end the
turn with no assistant text (empty turn). Two changes:
- MAX_AGENT_STEPS = 20 (was a magic stepCountIs(8)) so multi-search turns
aren't cut off mid-investigation.
- prepareStep reserves the LAST allowed step for a text-only synthesis:
toolChoice 'none' + a FINAL_STEP_INSTRUCTION appended to (not replacing)
the system prompt, so a tool-heavy turn always ends with a real answer.
Logic extracted into the pure, exported prepareAgentStep(stepNumber, system)
for unit testing; earlier steps return undefined (default behavior).
Implements docs/backlog/ai-chat-step-limit-and-forced-final-answer.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
