fix: stdin piping text

[felipefreitag]

Adds the --text-file option and allows piping files to both --html-file and --text-file options.

echo "<h1>Hello</h1>" | resend emails send --from you@domain.com --to user@example.com --subject "Hi" --html-file -

cat body.txt | resend emails send --from you@domain.com --to user@example.com --subject "Hi" --text-file -

echo '[{"from":"you@domain.com","to":["user@example.com"],"subject":"Hi","text":"Hello"}]' | resend emails batch --file -

Decided to move on with separate --text and --text-file options because otherwise we'd need a file indicator that would be less explicit (i.e. cURL uses @ to indicate files). Opted for the more explicit approach for now.

[cubic-dev-ai]

cubic analysis

7 issues found across 13 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/commands/broadcasts/update.ts">

<violation number="1" location="src/commands/broadcasts/update.ts:89">
P1: According to linked Linear issue ENG-4686, `--text -` should read from stdin, but this change only supports stdin via `--text-file -`, so `--text -` still sends a literal `"-"` body.</violation>
</file>

<file name="src/commands/emails/send.ts">

<violation number="1" location="src/commands/emails/send.ts:275">
P2: According to linked Linear issue ENG-4686, `--text -` should read stdin, but this code still treats `-` as a literal text value unless `--text-file` is used.</violation>
</file>

<file name="src/commands/templates/create.ts">

<violation number="1" location="src/commands/templates/create.ts:100">
P2: `--text -` is still treated as a literal string instead of reading stdin, so the ENG-4686 behavior remains unfixed for this command.

According to linked Linear issue ENG-4686, this should read stdin.</violation>
</file>

<file name="tests/commands/emails/send.test.ts">

<violation number="1" location="tests/commands/emails/send.test.ts:607">
P2: According to linked Linear issue ENG-4686, stdin piping must work with `--text -`, but the new coverage validates `--text-file -` instead. Add/adjust tests (and implementation if needed) for `--text -` so the reported bug is actually enforced.</violation>
</file>

<file name="src/commands/broadcasts/create.ts">

<violation number="1" location="src/commands/broadcasts/create.ts:27">
P2: According to linked Linear issue ENG-4686, stdin piping is required for `--text -`, but this change adds `--text-file -` instead and does not implement `--text -` stdin behavior.</violation>

<violation number="2" location="src/commands/broadcasts/create.ts:49">
P3: The new help text says users must provide exactly one body option, but the command accepts both HTML and text together. Update wording to match actual behavior.</violation>
</file>

<file name="tests/commands/broadcasts/update.test.ts">

<violation number="1" location="tests/commands/broadcasts/update.test.ts:248">
P2: According to linked Linear issue ENG-4686, tests should validate stdin piping via `--text -`, but the new cases only validate `--text-file`, leaving the required bug path untested.</violation>
</file>

Linked issue analysis

Linked issue: ENG-4686: Stdin piping with --text -

Status	Acceptance criteria	Notes
❌	When user passes --text -, the CLI should read stdin (Unix convention)	Introduced --text-file but did not make --text accept '-'
✅	Provide a --text-file option that accepts '-' to read stdin	--text-file option added and used to set text from readFile
✅	readFile implementation treats '-' as stdin and reads from fd 0	readFile reads from fd 0 when filePath === '-'
✅	Support piping stdin for batch command via --file -	Batch command help/examples updated and tests check readFile called
✅	Error when both --html-file and --text-file are '-' (avoid reading stdin twice)	Added explicit checks and outputError when both equal '-'
✅	Warn when both inline (--text/--html) and file flags provided; file wins	Writes warning to stderr and uses file value when both provided
✅	Add tests covering stdin/file behavior across relevant commands	Many tests added for send, batch, templates, broadcasts for '-' behaviour
✅	Detect empty required flags and error invalid_options (e.g., empty --from/--subject)	Added empty-flag validation and tests for empty flags
✅	Update help text & examples to indicate using '-' for stdin where supported	Help texts and examples updated across commands to mention '-' usage

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P1: According to linked Linear issue ENG-4686, --text - should read from stdin, but this change only supports stdin via --text-file -, so --text - still sends a literal "-" body.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At src/commands/broadcasts/update.ts, line 89:

<comment>According to linked Linear issue ENG-4686, `--text -` should read from stdin, but this change only supports stdin via `--text-file -`, so `--text -` still sends a literal `"-"` body.</comment>

<file context>
@@ -54,24 +61,51 @@ Variable interpolation:
+    }
+
     let html = opts.html;
+    let text = opts.text;
 
     if (opts.htmlFile) {
</file context>

[cubic-dev-ai]

P2: According to linked Linear issue ENG-4686, stdin piping must work with --text -, but the new coverage validates --text-file - instead. Add/adjust tests (and implementation if needed) for --text - so the reported bug is actually enforced.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At tests/commands/emails/send.test.ts, line 607:

<comment>According to linked Linear issue ENG-4686, stdin piping must work with `--text -`, but the new coverage validates `--text-file -` instead. Add/adjust tests (and implementation if needed) for `--text -` so the reported bug is actually enforced.</comment>

<file context>
@@ -572,6 +572,279 @@ describe('send command', () => {
+    }
+  });
+
+  test('--text-file - reads from stdin', async () => {
+    spies = setupOutputSpies();
+
</file context>