A free skill that reviews your system design against the 7 building blocks and the non-functional "-ilities": what scales, what breaks, and the questions a senior would ask.
Paste a design doc, describe your architecture, or share a diagram. Review with Blocks decomposes it into blocks and forces, flags the wrong and missing ones, rates the "-ilities" that actually matter for your system, and hands you the questions a senior would ask in the review. It judges the architecture, not your code style. It's the review end of design → build → review.
A design doc, an architecture description, or a diagram — including the output of Design with Blocks.
Decomposes your design into the 7 blocks + 3 forces, and flags the wrong, missing, or over-engineered ones.
Only the ones your system makes load-bearing — each holds, at-risk, or gap, with the tradeoff it costs.
The 3–5 pointed questions that expose whether the design really understood its forces.
Run on a photo-gallery design. Notice it respects the design's intentional restraint, then finds the two things that actually matter for this system.
VERDICT
The shape is right — the restraint is the design, not a flaw.
Two gaps, both on the source-of-truth file store.
FINDINGS
[BLOCKER] Durability — irreplaceable photos, only the laptop as a
second copy, no backup/replication named.
[RISK] Write-auth — "no login" is fine for reads, but the publish
endpoint still needs to authenticate the write.
[POLISH] Tag/date search scans raw files — fine now; revisit at scale
(a database today would be over-engineering).
THE -ILITIES THAT MATTER HERE
Latency ✅ holds KV caches + CDN
Availability ✅ holds static reads survive the laptop offline
Durability ⛔ gap file store has no backup story
Consistency ⚠️ at-risk partial-publish window on flaky wifi
Write-security ⚠️ at-risk publish needs a token
A SENIOR WOULD ASK
If the file store loses a disk tomorrow, what's the recovery path —
and is your laptop a real backup, or just the working copy?
Free and open source (Apache-2.0). Pick the surface you already use.
Listed in Claude Code's plugin directory (reviewed by Anthropic, October 2026).
Then run /review-with-blocks and give it your design. Updates: /plugin marketplace update systemthinkinglab.
Installs into your project's .agents/skills/review-with-blocks/ as an Agent Skill. The skill is built and tested in Claude Code.
Settings → Capabilities → Skills → Add Skill. Download the repo, then upload the review-with-blocks/skills/review-with-blocks folder.
The courses are the graded reps: feedback on your own judgment, under real constraints.
The review tells you where this design holds and where it breaks. The skill to produce that judgment yourself, to look at any architecture and know which -ilities matter and which blocks buy them, starts with Course 0. Courses I-IV build it: hands-on discovery labs, real design challenges, and case studies of Instagram, Netflix, and Uber.
Free five-day course