fix(dspy): Guard use_tip on tip value in GroundedProposer to avoid rendering None in prompt

[detail-app]

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Detail bug report: View on Detail

📝 Changes Description

Closes Unknown issue

Bug
GroundedProposer (MIPROv2's instruction proposer) accepts use_tip and set_tip_randomly flags. When set_tip_randomly=False — a configuration explicitly supported by PR stanfordnlp#3919 — selected_tip stays None, but the constructor default use_tip=True was left unchanged. The generation signature still declared the tip input field and tip=None was forwarded into the prompt, where DSPy's adapter rendered it as the literal string "None", producing a meaningless [[ ## tip ## ]]\nNone block the LM is told to follow. The analogous use_instruct_history flag was already guarded with and instruction_history; use_tip lacked the equivalent guard.

Fix
Guard use_tip on whether a real tip value was supplied, mirroring the existing use_instruct_history guard in dspy/propose/grounded_proposer.py:

use_tip=self.use_tip and bool(tip),

This omits the tip field from the signature when no real tip is present, so the adapter no longer renders None. Only the buggy configuration (use_tip=True with tip=None) changes; all other paths (real tip supplied, use_tip=False, set_tip_randomly=True drawing "none" or a real tip) behave identically.

Testing

• Added regression tests in tests/propose/test_grounded_proposer.py using a RecordingDummyLM that captures the exact prompt sent to the rollout LM copy (shared by reference through BaseLM's shallow copy). They assert the tip block is omitted when tip=None — both via the direct propose_instruction_for_predictor and the end-to-end propose_instructions_for_program with set_tip_randomly=False — and that a real tip is still rendered. These tests fail without the one-line fix and pass with it.
• Unit tests (tests/propose/), the broader optimizer suite (tests/teleprompt/), ruff check, and ruff format --check on the test file all pass. The project configures no typechecker; an ad-hoc mypy run shows no new type errors versus the original file (all pre-existing).
• A live-LM smoke test could not be run: no LM credentials or local server are available in this environment (confirmed via LMServerError: Missing credentials and LMTransportError: Connection error on attempted setup). The prompt-content invariant the smoke would verify is instead asserted deterministically by the RecordingDummyLM regression tests.

✅ Contributor Checklist

• Pre-Commit checks pass locally (ruff check); remote CI pending run
• Title of your PR / MR corresponds to the required format (fix(dspy): ...)
• Commit message follows required format fix(dspy): Guard use_tip on tip value in GroundedProposer to avoid rendering None in prompt

⚠️ Warnings

• Authored by Detail (automatic fixes). Verified locally as described above; the live-LM round-trip was not exercisable here (no credentials/endpoint) but is covered deterministically by the prompt-capture unit tests.
• grounded_proposer.py retains some pre-existing ruff format style nits unrelated to this change; left untouched to keep the diff minimal (CI enforces ruff check, not ruff format).

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[greptile-apps]

Greptile Summary

This PR prevents GroundedProposer from declaring a tip input field when no meaningful tip value exists, avoiding a literal None block in generated prompts.

• Conditions signature construction on both the configured use_tip flag and the supplied tip value.
• Preserves prompt rendering when a real tip is supplied.
• Adds direct and end-to-end regression coverage using captured rollout prompts.

Confidence Score: 5/5

The PR appears safe to merge; the focused guard fixes the unwanted prompt field without changing valid tip behavior.

No actionable failures remain: all reachable falsey tip values represent the intended absence of a tip, non-empty tips remain rendered, and the regression tests exercise the affected direct and end-to-end paths.

Important Files Changed

Filename	Overview
dspy/propose/grounded_proposer.py	Correctly omits the optional tip field for None or the intentionally empty no-tip value while preserving non-empty tips.
tests/propose/test_grounded_proposer.py	Adds focused prompt-capture tests covering absent tips, supplied tips, and the end-to-end non-random configuration.

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