"We didn't tell her that I was coming," = "On ne lui a pas dit que je venais,"

Question

Could someone clarify why imperfect is used in the above example? I thought it would be future (je viendra). The linked lesson is "Expressing continuing action with the imperfect tense in French" but this does not seem like a continuing action? And the rest of the sentence is in future tense as well. 
Thanks in advance!

Céline Pickard · Accepted Answer

Bonjour Elysia,
This is a case of "concordance des temps", i.e. sequence of tenses. The main verb is in Le Passé Composé, so the verb from the subordinate clause will be reported in a past tense too. At the time of the main action (not telling her), the state of the person "coming" was already an ongoing plan (decision/plan was already made) in the background. Hence, L'Imparfait.
On ne lui a pas dit que je venais = We didn't tell her I was coming
The following "On ne lui a pas dit que je viendrais" is possible in French althought the translation would be different (= "We didn’t tell her I would come") and it suggests the "coming" is not necessarily already underway. Using L'Imparfait (Indicatif mood) makes it more factual, i.e. a plan already in motion.
I hope this is helpful.
Bonne journée !

Anne Davies · Answer

Also, "que je venais" is reported speech: a main clause in passé composé will trigger the use of l’imparfait.  
 
 Link from Lawless French https://www.lawlessfrench.com/grammar/indirect-speech/