Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/schemas/createRenderSchema.ts`:
- Around line 9-19: The crop/resize schemas allow invalid or no-op ops: tighten
the zod schemas in createRenderSchema.ts by (1) validating aspect (the aspect
field in the type: "crop" object) against an expected format (e.g. "W:H" numeric
pair) using a string refinement, (2) adding a refinement on the crop variant
(type: "crop") to require either a valid aspect OR both width and height present
and positive, and (3) adding a refinement on the resize variant (type: "resize")
to require at least one of width or height present and positive; update any
error messages to be clear so buildFfmpegArgs will never receive
missing/negative dimensions or produce scale=-1:-1.
- Around line 36-42: The createRenderPayloadSchema currently allows zero or both
of video_url and audio_url; update createRenderPayloadSchema to enforce exactly
one input URL by adding a schema-level refinement (e.g., using .refine or
.superRefine) that checks that exactly one of the two optional fields
(video_url, audio_url) is present and non-empty, and return a clear validation
error message when the check fails; keep the existing field validators for
video_url and audio_url and reference createRenderPayloadSchema, video_url, and
audio_url when making the change.

In `@src/tasks/__tests__/createRenderTask.test.ts`:
- Around line 111-118: The test name "rejects empty operations array" mismatches
the assertion for createRenderPayloadSchema.safeParse
(expect(result.success).toBe(true)); either rename the test to reflect that an
empty operations array is valid (e.g., "accepts empty operations array") or
invert the assertion to expect(false) so it truly asserts rejection; update the
spec title referencing createRenderPayloadSchema and the test block name passed
to it() accordingly to keep behavior and intent aligned.

In `@src/tasks/createRenderTask.ts`:
- Around line 133-145: The overlay_text case in createRenderTask.ts builds the
drawtext filter but ignores the op.font field declared in the schema
(createRenderSchema.ts); update the filter construction in the "overlay_text"
branch to include the font by adding a fontfile=${op.font} entry (or
conditionally include it only when op.font is provided) to the filter array so
the drawtext filter uses the requested font; ensure you reference op.font (and
escape it if needed) and keep the rest of the drawtext entries intact.
- Around line 148-166: In the mux_audio case fix the FFmpeg argument ordering
and mapping: ensure all input flags added to extraInputs (including
op.audio_url) are pushed into args before output-side options like -vf and
mappings (reorder where args.push(...extraInputs) occurs relative to
args.push("-vf", ...)); and when op.replace is false, change the amix usage to
produce a labeled filter output and map that label (e.g., build a filter like
combining [0:a][1:a]amix=inputs=2 into a label and then push a -map for that
label) so audioMapping maps the mixed output rather than the original tracks
(update how audioMapping is constructed in the mux_audio branch accordingly,
referencing mux_audio case, extraInputs, audioMapping, videoFilters and args).
- Around line 44-45: The task builds a video-centric pipeline unconditionally
(uses inputPath/outputPath, maps 0:v:0, forces -c:v libx264/-pix_fmt/+faststart
and returns video/*), which breaks audio-only payloads (payload.audio_url);
update createRenderTask to detect audio-only payloads (presence of
payload.audio_url and absence of video sources) and branch: when audio-only, set
outputPath/extension and MIME to an audio type, remove video mapping and video
codec/pix_fmt/faststart options, map the audio stream(s) only (e.g., 0:a:0), and
set appropriate ffmpeg args for audio encoding; when video is present, keep the
existing video pipeline behavior. Ensure any metadata returned reflects audio
MIME/type when audio-only.

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/tasks/createRenderTask.ts">

<violation number="1" location="src/tasks/createRenderTask.ts:96">
P1: Custom agent: **Flag AI Slop and Fabricated Changes**

The `buildFfmpegArgs` function contains the core logic of this PR (5 operation types, ~60 lines of ffmpeg argument construction including aspect-ratio math, text escaping, and audio mapping) but is not exported and has zero test coverage. All 12 tests only check schema parsing and static task config properties — none exercise the actual behavior this PR adds. Export this function and add unit tests for each operation type, especially the crop aspect-ratio branch, the `overlay_text` escaping, and the `mux_audio` replace vs. mix paths.</violation>

<violation number="2" location="src/tasks/createRenderTask.ts:153">
P1: The `mux_audio` with `replace: false` generates incorrect ffmpeg arguments. The `amix` filter output is never mapped — the subsequent `-map 0:a -map 1:a` references the original unmixed streams, so the audio mixing never actually happens. Also, if any video filters are present, the combination of `-vf` and `-filter_complex` will cause ffmpeg to error.

The correct approach labels the filter inputs/outputs and maps only the mixed result.</violation>
</file>

<file name="src/schemas/createRenderSchema.ts">

<violation number="1" location="src/schemas/createRenderSchema.ts:3">
P0: `z.discriminatedUnion()` does not exist in Zod v4 (this project uses zod@4.3.6). This will throw a `TypeError` at runtime. In Zod v4, use `z.union()` instead — it automatically detects discriminated unions by shared literal fields.</violation>

<violation number="2" location="src/schemas/createRenderSchema.ts:11">
P2: All fields in the `crop` operation (`aspect`, `width`, `height`) are optional, so `{ type: "crop" }` passes validation despite being semantically invalid — ffmpeg's `crop=` filter needs at least a dimension or aspect ratio. Consider adding a `.refine()` to require at least one of these fields. The same issue applies to the `resize` operation below.</violation>
</file>

<file name="src/tasks/__tests__/createRenderTask.test.ts">

<violation number="1" location="src/tasks/__tests__/createRenderTask.test.ts:111">
P2: Test name says "rejects empty operations array" but the assertion expects `result.success` to be `true`. Rename to accurately describe the behavior, e.g. `"accepts empty operations array"`.</violation>
</file>

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/content/buildRenderFfmpegArgs.ts">

<violation number="1" location="src/content/buildRenderFfmpegArgs.ts:51">
P2: When both `width` and `height` are omitted (both are optional in the schema), this produces `scale=-1:-1` which is invalid — ffmpeg requires at least one concrete dimension when using `-1`. Add a guard or add a `.refine()` to the schema requiring at least one dimension.</violation>

<violation number="2" location="src/content/buildRenderFfmpegArgs.ts:67">
P2: The `color` and `stroke_color` values are interpolated directly into the colon-delimited drawtext filter string without sanitization. A value containing `:` (e.g., `"white:enable=0"`) would inject additional ffmpeg drawtext parameters. Either validate color format in the schema (e.g., with a regex) or escape colons in these values.</violation>
</file>

<file name="src/tasks/createRenderTask.ts">

<violation number="1" location="src/tasks/createRenderTask.ts:11">
P2: Custom agent: **Flag AI Slop and Fabricated Changes**

Unused imports `escapeDrawtext` and `stripEmoji` — these are only needed inside `buildRenderFfmpegArgs`, which already imports them. Leftover dead imports from the extraction refactor.</violation>
</file>

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/content/buildRenderFfmpegArgs.ts`:
- Around line 77-94: The mux_audio branch uses incorrect amix syntax and places
-vf before all inputs; update the "mux_audio" case in buildRenderFfmpegArgs.ts
so that when op.replace is false you build a labeled filter_complex like
"[0:a][1:a]amix=inputs=2[aout]" and map the mixed audio with "-map", "[aout]"
(instead of mapping "0:a" and "1:a" directly), while keeping the replace=true
behavior mapping video and the single audio input ("-map", "0:v:0", "-map",
"1:a:0"). Also change argument ordering so extraInputs (the "-i", op.audio_url"
entries) are added before applying output options like "-vf" (move the
videoFilters/args.push("-vf", ...) after you push extraInputs and audioMapping)
to ensure FFmpeg input-bound options are correctly ordered.
- Around line 39-44: The current crop logic in the "crop" case uses op.aspect to
build a crop string that can produce dimensions larger than the source (e.g.,
`crop=iw:iw*${h}/${w}`) and fail; update the logic in buildRenderFfmpegArgs so
that after parsing op.aspect into w and h you compute the targetAspect = w/h and
sourceAspect = sourceWidth/sourceHeight (or compare using iw and ih
algebraically) and then choose the crop formula based on whether sourceAspect >
targetAspect or not: if source is wider than target, crop width to match target
using width = ih * targetAspect and height = ih (crop by width); otherwise crop
height using width = iw and height = iw / targetAspect (crop by height); push
the resulting safe crop filter string to videoFilters and ensure you only push
when w and h are valid numbers.

---

Nitpick comments:
In `@src/content/__tests__/buildRenderFfmpegArgs.test.ts`:
- Around line 113-144: Add two assertions to the buildRenderFfmpegArgs tests:
first, add a case calling buildRenderFfmpegArgs with a mux_audio operation where
replace: false and assert the mixed-audio mapping is produced (i.e., the
original audio input remains mapped and the new audio is appended, checking the
positions of "-map" entries similar to the existing replace=true test but
expecting original audio map like "0:a:0" and new audio like "1:a:0"); second,
add a combined test that includes video filters (e.g., crop and overlay_text)
plus a mux_audio and assert that all input URLs/“-i” entries (the audio input
string) appear in args before output options like "-vf" (use args.indexOf to
compare positions for the audio input and "-vf"), ensuring ffmpeg input ordering
is preserved when replace is false.

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/content/runFfmpeg.ts">

<violation number="1" location="src/content/runFfmpeg.ts:13">
P1: ffmpeg stderr output can exceed the default 1 MB `maxBuffer`, killing the process with `ERR_CHILD_PROCESS_STDIO_MAXBUFFER`. Increase the limit to accommodate verbose ffmpeg output on long or complex renders.</violation>
</file>

<file name="src/content/downloadMediaToFile.ts">

<violation number="1" location="src/content/downloadMediaToFile.ts:12">
P2: Downloading large video/audio files entirely into an in-memory `Buffer` before writing to disk risks high memory usage or OOM in the task worker. Consider streaming the response body directly to the file using `node:stream/promises` `pipeline` with `fs.createWriteStream`, which avoids holding the full file in memory.</violation>
</file>

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/schemas/createRenderSchema.ts">

<violation number="1" location="src/schemas/createRenderSchema.ts:28">
P2: Color regex accepts invalid 5- and 7-digit hex values (e.g. `#12345`, `#1234567`). Restrict to the four valid CSS hex lengths: 3, 4, 6, or 8 digits.</violation>
</file>

Verify each finding against the current code and only fix it if needed.

Duplicate comments:
In `@src/content/buildRenderFfmpegArgs.ts`:
- Around line 93-101: The ffmpeg "-vf" output option is being pushed before
additional input declarations, which can break ffmpeg; in the
buildRenderFfmpegArgs flow move the blocks that push extraInputs and
audioMapping (args.push(...extraInputs) and args.push(...audioMapping)) so they
occur before the videoFilters handling, and then push the "-vf"
(videoFilters.join(",")) after those input-related pushes; update the code
around the videoFilters / extraInputs / audioMapping logic (references:
videoFilters, extraInputs, audioMapping, args) so all "-i" inputs are added to
args prior to any output options like "-vf".
- Around line 40-48: The crop aspect handling in buildRenderFfmpegArgs (inside
the "crop" case where op.aspect is parsed into [w,h] and videoFilters is pushed)
can produce crop dimensions that exceed the source; replace the current w>h
ternary expression with a conditional that compares the source aspect (iw/ih) to
the target aspect (w/h) and selects a crop that is bounded by the source
dimensions (e.g., use an ffmpeg conditional expression or calculate width/height
so neither exceeds iw or ih). Ensure you still parse op.aspect into w and h, but
build the crop filter using a conditional based on iw/ih vs w/h so the resulting
crop width and height never exceed the source frame.

In `@src/schemas/createRenderSchema.ts`:
- Around line 40-46: The createRenderPayloadSchema currently allows both or
neither of video_url and audio_url; add a zod refinement on
createRenderPayloadSchema to require exactly one of video_url or audio_url is
present and non-empty so validation fails early with a clear message. Locate
createRenderPayloadSchema and attach a .refine(...) that checks
(Boolean(video_url) !== Boolean(audio_url)) and returns a custom error message
like "exactly one of video_url or audio_url must be provided" so payloads with
both or neither are rejected.

---

Nitpick comments:
In `@src/content/runFfmpeg.ts`:
- Around line 12-14: The runFfmpeg function can overflow the default execFile
buffer or hang; update runFfmpeg to accept optional exec options (e.g., timeout
and maxBuffer) and pass them into execFileAsync so callers can increase
maxBuffer (e.g., 10MB+) and set a sensible timeout. Specifically, modify the
runFfmpeg signature (runFfmpeg) to accept an optional options parameter and
forward that object to execFileAsync("ffmpeg", args, options) so you can
configure timeout and maxBuffer when invoking FFmpeg.

In `@src/schemas/createRenderSchema.ts`:
- Around line 10-11: The aspect field in the createRenderSchema (where type:
z.literal("crop") and aspect: z.string().optional()) currently allows any string
but buildRenderFfmpegArgs expects "W:H" (e.g., "9:16"); update the schema to
validate aspect with a regex that enforces two positive integers separated by a
colon (e.g., /^\d+:\d+$/) and keep it optional (use aspect:
z.string().regex(...).optional()) so invalid values like "invalid" or "16-9" are
rejected at validation time.

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/content/buildRenderFfmpegArgs.ts">

<violation number="1" location="src/content/buildRenderFfmpegArgs.ts:86">
P2: In audio-only mode, `mux_audio` fallback can remap to a second input and drop earlier audio edits (e.g., `trim`).</violation>
</file>

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/tasks/ffmpegEditTask.ts`:
- Around line 36-37: The temp directory stored in tempDir (created via
join(tmpdir(), `render-${randomUUID()}`) in ffmpegEditTask) is never removed;
update the cleanup in the finally block (the section that currently deletes
individual files around lines 66-70) to also remove the entire tempDir after
deleting files by invoking a recursive delete (e.g., fs.rm or fs.promises.rm
with recursive/force) or equivalent rmdir call, and guard it with try/catch so
failures don't mask other errors; reference tempDir and the existing per-file
cleanup code to add this final directory removal.
- Around line 39-40: The temp filenames and upload MIME are hardcoded for video;
when payload.audioOnly is true, change the inputPath to use an audio extension
(e.g., input.wav or input.<inferred audio ext>) instead of "input.mp4", set
outputPath extension accordingly, and ensure the upload uses an audio MIME like
"audio/${payload.output_format}" rather than "video/${payload.output_format}";
update the logic around inputPath, outputPath and the MIME type construction so
it branches on payload.audioOnly (or inspects payload.output_format) to pick the
correct file extension and "audio/" vs "video/" media type while keeping
existing variable names inputPath, outputPath and payload.output_format.

---

Duplicate comments:
In `@src/schemas/ffmpegEditSchema.ts`:
- Line 11: The aspect field currently allows any string which can break
buildRenderFfmpegArgs.ts that expects "W:H"; change the aspect schema in
ffmpegEditSchema (the aspect property) to validate the "W:H" integer pattern
(e.g. use z.string().regex(/^\d+:\d+$/, 'aspect must be in "W:H" integer
format').optional()) so invalid values like "foo" or "9-16" are rejected with a
clear error message.

---

Nitpick comments:
In `@src/schemas/ffmpegEditSchema.ts`:
- Around line 3-38: Replace the top-level z.union with
z.discriminatedUnion("type", [...]) for editOperationSchema to leverage the
literal "type" discriminator (keep each variant object schemas—including the
.refine calls on the crop and resize schemas—attached to their respective object
definitions); update the definition line from z.union([...]) to
z.discriminatedUnion("type", [...]) and ensure the crop and resize objects still
call .refine(...) as before so their validation remains intact; if you
intentionally keep z.union, add a short comment by editOperationSchema
explaining the tradeoff for the refine usage.

In `@src/tasks/__tests__/ffmpegEditTask.test.ts`:
- Around line 163-177: The tests repeatedly use dynamic imports of
ffmpegEditTask which may return a cached module across tests; to ensure test
isolation either import ffmpegEditTask once at the top of the describe block and
reuse that value for the three tests (so ffmpegEditTask, ffmpegEditTask.id,
ffmpegEditTask.schema, ffmpegEditTask.machine, ffmpegEditTask.maxDuration are
read from the same stable import), or add vi.resetModules() in a beforeEach to
clear the module cache before each test so each dynamic import yields a fresh
module instance.

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/tasks/ffmpegEditTask.ts">

<violation number="1" location="src/tasks/ffmpegEditTask.ts:21">
P1: Custom agent: **Flag AI Slop and Fabricated Changes**

This change violates the “Flag AI Slop and Fabricated Changes” clause for PR/docs claims not implemented: the PR claims a `create-render` task, but the code registers `ffmpeg-edit`. Align the task ID with the stated API contract or correct the PR metadata.</violation>
</file>

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/tasks/__tests__/ffmpegEditTask.test.ts`:
- Around line 112-122: The test currently may pass vacuously because it only
checks for absence of audio_url when parse succeeded; explicitly assert the
parse succeeded before further assertions by adding an assertion on
createRenderPayloadSchema.safeParse(...) result (e.g.,
expect(result.success).toBe(true)) and then perform the property check on
result.data; reference the test block using the existing
createRenderPayloadSchema and the "does not accept audio_url param" test to
locate where to add the success assertion.

---

Duplicate comments:
In `@src/content/buildRenderFfmpegArgs.ts`:
- Around line 69-74: The crop math in buildCropFilter only looks at target
orientation (w >= h) and can produce crop values larger than the source (causing
ffmpeg failures); update buildCropFilter to compare source aspect to target
aspect (use ffmpeg expressions like iw/ih vs w/h) and emit a conditional crop
expression that clamps to source bounds (use ffmpeg min() or if() expressions so
the computed crop width/height never exceed iw/ih, e.g. choose cropping by width
when source is wider than target and by height otherwise, but expressed with
safe ffmpeg arithmetic), referencing buildCropFilter and the local w,h/op.aspect
variables so the new expression always yields values within input dimensions.

In `@src/schemas/ffmpegEditSchema.ts`:
- Around line 13-18: The crop schema currently allows invalid aspect strings and
one-sided dimensions; tighten validation on the crop object (the crop schema
with keys aspect, width, height) by: 1) validating aspect with a strict pattern
(e.g., a regex matching "N:M" positive integers) instead of plain z.string(); 2)
ensure width and height remain positive ints but enforce that if one of width or
height is provided the other must also be present (use a .refine on the crop
object to require both or neither); and 3) keep the overall refine that requires
at least aspect or both dimensions so invalid combinations (malformed aspect or
lone width/height) are rejected.

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/schemas/ffmpegEditSchema.ts">

<violation number="1" location="src/schemas/ffmpegEditSchema.ts:3">
P1: Custom agent: **Flag AI Slop and Fabricated Changes**

PR description claims mux_audio/audio-only edits are supported, but this schema change removes the mux_audio operation and makes video_url required, so that behavior isn’t implemented. Update the PR description or restore mux_audio support to avoid shipping misleading documentation.</violation>
</file>

<file name="src/content/__tests__/buildRenderFfmpegArgs.test.ts">

<violation number="1" location="src/content/__tests__/buildRenderFfmpegArgs.test.ts:145">
P1: Custom agent: **Flag AI Slop and Fabricated Changes**

This test claims to verify mux_audio handling, but it never passes a mux_audio operation. As written, it only tests the trim path and doesn’t validate the claimed behavior.</violation>

<violation number="2" location="src/content/__tests__/buildRenderFfmpegArgs.test.ts:157">
P1: Custom agent: **Flag AI Slop and Fabricated Changes**

This test only asserts that `args` is non-empty, which doesn’t verify the claimed signature change at all. It reads like a placeholder rather than a real validation.</violation>
</file>

<file name="src/content/buildRenderFfmpegArgs.ts">

<violation number="1" location="src/content/buildRenderFfmpegArgs.ts:35">
P2: Guard against malformed aspect strings before adding a crop filter. With the current helper, any non-"w:h" aspect that still passes schema validation emits `crop=-1:-1`, which doesn't reflect a valid requested crop. Consider validating the aspect format in the schema or skipping the crop when parsing fails.</violation>
</file>