Comparing four possible rhetorical readings

Fronting the Subject: Restriction, Reinforcement and the al-Jurjani–al-Sakkaki Debate

To distinguish the available readings of fronting, keep overt nouns, pronouns, obstacles and context separate.

ExpressionPossible rhetorical force
زيد قائمPlain assertion or reinforcement; no automatic exclusivity
أنا قمتReinforcement or restriction against another agent
ما أنا قلت هذاFocused denial that the speech is attributable to me
رجل جاءنيCorrection of an assumption about kind or number in some contexts

The table is a diagnostic, not a universal ruling: syntactic form and rhetorical significance must not be equated.