Short clitics versus long pronouns

In the accusative, dative, and genitive cases, Czech personal pronouns split into two sets:

• Short forms (Clitics): mě, tě, ho, mu, mi, ti, se, si. (Note: se and si are technically reflexive pronouns, but they are included here because they share the exact same clitic rules). These are neutral and unstressed. They strictly follow Wackernagel's Law, meaning they must sit in the second position of the clause, attaching to the first stressed block of words. Because they are unstressed, they can never start a sentence.
• Long forms: mne/tebe, jeho, jemu, mně, tobě, sebe, sobě. These are stressed and are mandatory in three situations: 1) At the beginning of a sentence or standing alone. 2) For contrastive emphasis (e.g., Dám to tobě, ne jemu. [I will give it to YOU, not to him.]). 3) After prepositions (e.g., bez tebe [without you]).

Important Nuances:
1. When a 3rd-person pronoun directly follows a primary preposition, it must take an initial n- (e.g., bez něho [without him], k němu [to him], pro ni [for her]). With secondary or derived prepositions governing the dative case (like díky or kvůli), the bare form is sometimes allowed (e.g., díky jemu).
2. For the 1st person singular accusative/genitive, mě is the short form, but in modern spoken Czech, it also serves as the standard long form. The traditional long form mne is highly formal or literary. Additionally, for the accusative of on/ono, jej is a common formal or written alternative to ho.
3. Pronunciation trap: The forms mě (accusative/genitive) and mně (dative/locative) are spelled differently but sound exactly the same: [mňe].
4. No short/long pairs: Some pronouns, like ji [her], je [them], nás [us], and vás [you all], do not have distinct short and long forms. However, when they are unstressed, they still function as clitics and must obey the second-position rule. They only act as long forms (breaking the second-position rule) when they are stressed for emphasis or placed after a preposition.
5. Clitic clustering: When multiple short pronouns appear together, they stack in a strict order in the second position. The full clitic chain order is: Auxiliary verb (specifically the past tense jsem, jsi, jsme, jste and conditional bych, bys, by, bychom, byste, but never the present tense of být like je or jsou) -> Reflexive (se/si) -> Dative pronoun -> Accusative pronoun (including the pronoun to, which acts as an unstressed clitic in everyday speech and sits in this final accusative slot). Note two important rules: First, in the 2nd-person singular past tense, the auxiliary jsi obligatorily fuses with the reflexives se and si to form ses and sis (e.g., Koupil sis to?). Second, in the 3rd-person past tense, there is no auxiliary verb, meaning the clitic chain skips the first slot and starts directly with the reflexive or dative pronoun.
6. Other cases: The locative case only exists after prepositions, meaning it always uses long forms (with the n- prefix for the 3rd person). The instrumental case does not have short/long doublets. Instrumental forms (mnou, tebou, jím, jí, námi, vámi, jimi) are used in all positions, and 3rd-person instrumental pronouns still require the n- prefix after prepositions (e.g., s ním, před nimi).