Anatomy of a Conditional

A conditional sentence has two parts, called clauses:

the if-clause — the condition;
the result clause — what follows from it.

If the migration fails,        we roll back automatically.
└──── if-clause ────┘          └──── result clause ────┘

Neither clause is a complete sentence on its own. If the migration fails leaves the reader waiting; we roll back automatically is fine alone but says nothing about when.

The order can be reversed

Both orders are correct and mean the same thing. What changes is emphasis: whatever comes first is what you are drawing attention to.

Order	Example	Emphasis
Condition first	If the migration fails, we roll back automatically.	on the risk
Result first	We roll back automatically if the migration fails.	on the safeguard

In a status update you would write the first. In documentation describing a feature, the second.

The comma rule

This is one rule, and it is worth memorising because it is mechanical:

If-clause first → comma. Result clause first → no comma.

✅ If the build is red, don't merge.
✅ Don't merge if the build is red.
❌ Don't merge, if the build is red.
❌ If the build is red don't merge.

The last two are the errors that survive longest in strong learners' writing. English readers use the comma to know where the condition ends; when the condition comes second, the word if already marks the boundary and the comma is redundant.

Two-panel sketch of a sentence as a hinged door, comma as the hinge pin

Two panels side by side, plain line drawing, no colour. Left panel: a sentence drawn as two rectangular blocks joined by a small round hinge pin. The left block is labelled "IF-CLAUSE", the right block "RESULT". The hinge pin is drawn as a comma and sits between them. Right panel: the same two blocks, but swapped — "RESULT" is now on the left, "IF-CLAUSE" on the right — and where the hinge pin was there is now nothing, just the two blocks touching, with the word "if" printed on the left edge of the right-hand block. A thin curved arrow runs from the left panel to the right panel to show the swap.

линейный технический скетч, тонкая единообразная линия, подписи только латиницей заглавными буквами

Time is not tense

This is the single idea that unlocks the rest of the course.

Tense is the shape of the verb: fails, failed, had failed. Time is when the thing happens: now, yesterday, next Tuesday.

In conditionals these two come apart:

If it rains tomorrow, the outdoor stand-up is cancelled. — Present tense (rains), future time.
If we had more staging capacity, we would test this properly. — Past tense (had), present time. We are talking about today's capacity, not last year's.

So you cannot read the type off the verb form alone. You have to ask what the speaker is claiming about the world. That question — not the verb table — is what this course trains.

The four traditional patterns

You have probably met these. They are useful shorthand for four frequent cases, and the course uses their names, but they are not the whole system.

Name	Pattern	Example
Zero	if + present, present	If the cache key is missing, the service queries the database.
First	if + present, will + infinitive	If we merge today, we will ship on Friday.
Second	if + past simple, would + infinitive	If we had a second reviewer, the queue would move faster.
Third	if + past perfect, would have + past participle	If we had pinned the version, the build would not have broken.

Now look at four real sentences from an engineering week that fit none of these neatly:

If the retry succeeded, the alert must have been noise. (a guess about the past)
If the load test passes, deploy to production. (an instruction)
If you assess the data thoroughly, you might find the root cause. (a weakened prediction)
If we had pinned the version, the build would not be broken right now. (past cause, present result)

All four are ordinary English. They come later in this course. Mention them now only so that you stop expecting every conditional to carry a number.

What actually varies

Three things, and they vary more or less independently:

How real is the condition? — a fact, a likely future, an unlikely hypothesis, or something impossible.
What is the speaker doing? — stating, predicting, inferring, advising, ordering, regretting.
How committed is the speaker? — will / should / might / could express very different levels of confidence in the same slot.

The rest of the course walks through these three, one at a time.

Practice

A. Split and label. Mark the if-clause and the result clause.

We escalate to the on-call lead if the error rate stays above two percent for five minutes.
If you had joined the call, you would have heard the client's actual deadline.
If a request has no trace ID, the gateway generates one.

B. Reverse the order. Rewrite each sentence with the other clause first, and fix the punctuation.

If the pipeline is green, the artefact is published automatically.
The scheduler drops the job if the worker does not respond within thirty seconds.
If we had known about the rate limit, we would have batched the requests.

C. Comma check. Two of these four are punctuated wrongly. Find them.

If the token expires the client retries once.
The client retries once if the token expires.
If the token expires, the client retries once.
The client retries once, if the token expires.

D. Time, not tense. For each sentence, say what time it refers to, ignoring the verb shape.

If the disk filled up, the log rotation was misconfigured.
If I had root access, I would check that myself.
If the release is signed off today, QA starts tomorrow.

Answers

A. 1. if-clause: if the error rate stays above two percent for five minutes; result: We escalate to the on-call lead. 2. if-clause: If you had joined the call; result: you would have heard the client's actual deadline. 3. if-clause: If a request has no trace ID; result: the gateway generates one.

B. 4. The artefact is published automatically if the pipeline is green. 5. If the worker does not respond within thirty seconds, the scheduler drops the job. 6. We would have batched the requests if we had known about the rate limit.

C. Wrong: 7 (needs a comma after expires) and 10 (should have no comma). 8 and 9 are correct.

D. 11. Past time — an inference about something that already happened. 12. Present time, despite the past tense forms: I do not have root access now. 13. Future time, despite the present tense is signed off.