Agreement with a fronted direct object

In French, compound tenses with avoir (like le passé composé) usually leave the past participle in its base form. However, there is a specific rule for when the Direct Object (COD) is 'fronted' (placed before the verb). This rule also applies to pronominal verbs conjugated with être, where you must determine if the reflexive pronoun acts as a direct object (COD) or indirect object (COI).

1. When does this happen?
This occurs in three main scenarios:

• When using direct object pronouns (le, la, l', les, me, te, se, s', nous, vous). Note: The pronouns me, te, se, s', nous, and vous only trigger agreement when they function as the direct object, not the indirect object. For l', since it is always singular, you only need to identify the gender of the noun it replaces to make the correct agreement. (e.g., Il les a vus. - He saw them.)
• In relative clauses starting with que. (e.g., La pomme que j'ai mangée. - The apple that I ate.)
• In questions using quel or combien de. (e.g., Quelles fleurs as-tu achetées ? - Which flowers did you buy?)

2. How to agree:
Add the following endings to the past participle:

• -e for feminine singular
• -s for masculine plural
• -es for feminine plural

3. Special Cases:

• Indirect Objects: Never agree with an indirect object pronoun (like lui or leur). (e.g., Je leur ai parlé. - I spoke to them.)
• The pronoun 'en': The participle remains invariable when en is the object. (e.g., Des pommes, j'en ai mangé. - Apples, I ate some.)
• Verbs of Perception: With verbs like voir or entendre followed by an infinitive, only agree if the preceding object is the one doing the action. (e.g., La chanteuse que j'ai entendue chanter - The singer that I heard sing vs La chanson que j'ai entendu chanter - The song that I heard sung).
• faire/laisser + infinitive: The past participle fait never agrees when followed by an infinitive. For laissé, under the 1990 spelling reform it can remain invariable, but traditional grammar requires agreement if the preceding direct object performs the action of the infinitive. (e.g., Les robes qu'elle a fait faire. - The dresses she had made.)
• Semi-auxiliaries + infinitive: With verbs like vouloir, pouvoir, or devoir followed by an infinitive, the past participle is invariable if the preceding direct object belongs to the infinitive. (e.g., Les pommes que j'ai voulu manger. - The apples that I wanted to eat.)
• Reflexive verbs with body parts: If a pronominal verb is followed by a direct object (like parts of the body), the preceding reflexive pronoun acts as an indirect object, meaning no agreement is made (e.g., Elles se sont lavé les mains. - They washed their hands.).
• Impersonal verbs: The past participle of an impersonal verb never agrees. (e.g., La chaleur qu'il a fait. - The heat that there was.)
• The neuter pronoun 'l'': When l' stands for a whole idea or clause (meaning 'cela'), it does not trigger agreement. (e.g., La situation est pire que je ne l'avais imaginé. - The situation is worse than I had imagined it.)
• Verbs of measure, weight, and cost: Verbs like coûter, peser, or mesurer do not trigger agreement with their complement of measure. (e.g., Les cent euros que ce meuble a coûté. - The hundred euros that this piece of furniture cost.)
• 'que' vs 'qui': Remember that que is an object and triggers agreement, but qui is a subject and does not trigger agreement with a preceding object. (e.g., La femme qui a parlé - The woman who spoke vs La femme que j'ai vue - The woman that I saw).