Add polaroid + mosaic collage skills (#7)

Adds two transform-* skills that wrap the new `image merge` intent in @transloadit/node 4.9.0 (polaroid-stack and mosaic collage effects).

Author: kvz

README.md

@@ -47,11 +47,12 @@ Categories:
 - `integrate-*`: real-world integration guides (validated via `scenarios/` + E2E, but not requiring any test harness)
 
 Examples:
-- `generate-image`
 - `transform-generate-image-with-transloadit`
 - `transform-remove-background-with-transloadit`
 - `transform-describe-image-with-transloadit`
 - `transform-convert-markdown-to-pdf-with-transloadit`
+- `transform-build-polaroid-collage-with-transloadit`
+- `transform-build-mosaic-collage-with-transloadit`
 - `integrate-uppy-transloadit-s3-uploading-to-nextjs`
 
 The public catalog is whatever currently lives under [`skills/`](/Users/kvz/code/skills/skills).

skills/generate-image/SKILL.md

@@ -0,0 +1,63 @@
+---
+name: transform-build-mosaic-collage-with-transloadit
+description: One-off justified mosaic photo collage (N local images -> single image) using the official `@transloadit/node` CLI. Uses the `/image/merge` Robot's `mosaic` effect to build a tiled layout that keeps every photo fully visible, and downloads the result to an explicit output path via `--output`.
+when_to_use: |
+  Triggers when the user asks to create a mosaic collage, tile photos edge-to-edge, build a justified photo grid, make a Flickr-style photo layout, or compose N photos into a clean editorial collage that keeps every photo fully visible. Choose this over the polaroid skill when the vibe is clean and editorial (product grids, portfolio hero sections, social previews from a batch), and over `transform-generate-image-with-transloadit` when the input is N existing photos rather than a text prompt.
+---
+
+# Inputs
+
+- Two or more absolute paths to local input images
+- Optional output path; default to an explicit `collage.jpg` in the current working directory
+- Optional canvas size (`--width`, `--height`), default `1920×1200`
+- Optional `--seed` for deterministic layout
+
+# Prepare Instructions
+
+Resolve credentials in this order:
+- Shell environment variables
+- The current working directory `.env` only
+- `~/.transloadit/credentials`
+
+If your `.env` lives in a parent directory, export the variables into the shell first.
+
+# Run
+
+```bash
+npx -y @transloadit/node image merge \
+  --input ./photo-a.jpg \
+  --input ./photo-b.jpg \
+  --input ./photo-c.jpg \
+  --input ./photo-d.jpg \
+  --input ./photo-e.jpg \
+  --input ./photo-f.jpg \
+  --effect mosaic \
+  --width 1920 \
+  --height 1200 \
+  --border 12 \
+  --shuffle \
+  --format jpg \
+  --output ./collage.jpg
+```
+
+After the command finishes, confirm the image exists at the expected output path.
+
+# Tuning
+
+- `--border 12` sets both the outer canvas padding and the gutter width between tiles. Larger values give more breathing room.
+- `--background '#eee5d3'` fills the gutters and canvas padding (default). Hex codes or named colors both work.
+- `--background none` (with `--format png` or `--format webp`) produces a transparent canvas and transparent gutters.
+- `--shuffle` lets the Robot reorder inputs before solving the layout; combine with `--seed` to pin the shuffle.
+- `--seed 42` makes the mosaic solver deterministic — rerun with the same inputs to reproduce the same output.
+
+# Debug If It Fails
+
+```bash
+npx -y @transloadit/node assemblies get <assemblyIdOrUrl> -j
+```
+
+Notes:
+- Repeated `--input` values are bundled into a single `/image/merge` assembly.
+- The mosaic effect reads each input's aspect ratio and solves for a justified tile layout — portrait + landscape mixes generally produce more interesting layouts than uniform sizes.
+- Unlike the polaroid-stack effect, tiles are center-cropped to fit their allocated rectangle. Any portion of a photo can be cropped off — if every pixel matters, resize beforehand with `/image/resize` and `resize_strategy: fit`.
+- Prefer an explicit output filename (e.g. `./collage.jpg` or `./collage.png`) over a directory output so the extension is deterministic.

skills/transform-build-mosaic-collage-with-transloadit/SKILL.md

@@ -0,0 +1,61 @@
+---
+name: transform-build-polaroid-collage-with-transloadit
+description: One-off polaroid-stack photo collage (N local images -> single image) using the official `@transloadit/node` CLI. Uses the `/image/merge` Robot's `polaroid-stack` effect and downloads the result to an explicit output path via `--output`.
+when_to_use: |
+  Triggers when the user asks to create a polaroid collage, build a polaroid stack, arrange photos as polaroids, make a scrapbook-style photo collage, or lay out tilted overlapping instant photos on a canvas. Choose this over the mosaic skill when the vibe is personal or scrapbook-ish (event recaps, "year in photos"), and over `transform-generate-image-with-transloadit` when the input is N existing photos rather than a text prompt.
+---
+
+# Inputs
+
+- Two or more absolute paths to local input images
+- Optional output path; default to an explicit `collage.png` in the current working directory
+- Optional canvas size (`--width`, `--height`), default `1920×1200`
+- Optional `--seed` for deterministic layout
+
+# Prepare Instructions
+
+Resolve credentials in this order:
+- Shell environment variables
+- The current working directory `.env` only
+- `~/.transloadit/credentials`
+
+If your `.env` lives in a parent directory, export the variables into the shell first.
+
+# Run
+
+```bash
+npx -y @transloadit/node image merge \
+  --input ./photo-a.jpg \
+  --input ./photo-b.jpg \
+  --input ./photo-c.jpg \
+  --input ./photo-d.jpg \
+  --input ./photo-e.jpg \
+  --input ./photo-f.jpg \
+  --effect polaroid-stack \
+  --width 1920 \
+  --height 1200 \
+  --format png \
+  --output ./collage.png
+```
+
+After the command finishes, confirm the image exists at the expected output path.
+
+# Tuning
+
+- `--background '#eee5d3'` picks a warm beige canvas (default). Hex codes or named colors both work.
+- `--background none` (with `--format png` or `--format webp`) produces a transparent canvas.
+- `--coverage 1.5` is the default. Use `2.0`–`2.5` for bigger, more overlapping photos; `1.0` or below for smaller, more widely spaced polaroids.
+- `--seed 42` makes the layout deterministic — rerun with the same inputs to reproduce the same output.
+- `--shuffle` lets the Robot reorder inputs before laying them out.
+
+# Debug If It Fails
+
+```bash
+npx -y @transloadit/node assemblies get <assemblyIdOrUrl> -j
+```
+
+Notes:
+- Repeated `--input` values are bundled into a single `/image/merge` assembly.
+- The polaroid-stack effect works best with 4–12 inputs. Fewer than four tends to look sparse; more than a dozen starts to occlude heavily.
+- Each input is cropped to a square inside its polaroid frame — portrait or landscape originals both work.
+- Prefer an explicit output filename (e.g. `./collage.png` or `./collage.jpg`) over a directory output so the extension is deterministic.

skills/transform-build-polaroid-collage-with-transloadit/SKILL.md

@@ -1,6 +1,8 @@
 ---
 name: transform-generate-image-with-transloadit
 description: One-off image generation (prompt -> image file) using Transloadit via the `transloadit` CLI. Prefer `image generate` for text-only and input-guided generation, and use `--output` when you need a deterministic path.
+when_to_use: |
+  Triggers when the user asks to generate an image, create an image from a prompt, make an AI image, render a picture from text, or guide image generation with reference photos. Choose this for prompt-driven or prompt+input-guided generation of a local image file. Prefer this over the collage skills when the input is a text prompt rather than N existing photos to composite.
 ---
 
 # Run