Python: preserve message roles in ClaudeAgent._format_prompt - #7895
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Python: preserve message roles in ClaudeAgent._format_prompt#7895Praveen Kumar Mittal (mittalpk) wants to merge 1 commit into
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_format_prompt() joined every message's text with no role information, so in multi-agent orchestration (SequentialBuilder/ConcurrentBuilder) Claude couldn't tell its own prior turns apart from another agent's turns or the user's actual instruction. The Claude Agent SDK's streaming-input protocol only accepts user-role turns (it generates its own assistant turns), so per-message roles can't be sent on the wire. Instead, when the input is more than a single plain user turn, each message is now prefixed with its role as text (e.g. "[assistant]: ...") so Claude can still tell the turns apart. The common single-user-turn case is left unchanged.
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Fixes #7894.
ClaudeAgent._format_prompt()joined every message's text together with no role information at all, so a multi-agent orchestration (SequentialBuilder/ConcurrentBuilder) that hands an agent the accumulated conversation — including other agents' and the user's turns — loses all of that structure by the time Claude sees it. Everything reads as one undifferentiated blob sent as a singleuser-role turn.I originally proposed sending real per-message roles through the SDK's async-iterable
query()input (see the issue discussion), but testing that against the actual CLI showed the streaming-input protocol rejects any role other thanuseroutright (Error: Expected message role 'user', got 'assistant') — it generates its own assistant turns and won't accept synthetic ones. So the fix here instead labels each message with its role as visible text ([user]: .../[assistant]: ...) when there's more than a single plain user turn, so Claude can still tell who said what. The common single-user-message case is left exactly as it was, to avoid changing behavior for the overwhelming majority of calls.Verification:
git stashisolation).packages/claude/tests/suite passes (72 tests).ruff check/ruff format --checkclean on both changed files.mypyon the changed file shows the same 2 pre-existing, unrelated errors present on a cleanmaincheckout (confirmed viagit stash) — nothing introduced by this change.