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A comprehensive knowledge base for Claude.ai, Claude Code, Cowork, and API — from beginner to advanced.
The Page Was 90px Too Wide at 375px, and the Culprit Never Showed Up in querySelectorAll
When a pseudo-element causes horizontal overflow on phones, scanning elements finds nothing. A probe script that confirms the culprit by diff, and overflow fixes that keep sticky intact, with measurements.
Claude Said the File Was Created, but the Folder Was Empty — A Read-Back Check After Every Write
When a file-creation call reports success but nothing exists on disk, here is the order I use to narrow down the cause, plus a small script that reads back every write.
If You Wrote MCP Allow Rules as Just `mcp__servername` — Three Lines to Recheck After v2.1.299
Claude Code v2.1.299 changed MCP allow rules to match only the server they name. Here is how to audit older entries in settings.json, with a short Python script that does it.
I Preloaded a Scheduled Task with head -150: 15.6 KB Read, 3.3 KB for Today
A scheduled task preloaded its daily notes with head -150, and line count turned out to be no budget at all. A date-block reader with a byte ceiling, and how to avoid dropping ideas nobody has used yet.
43 Days Until Sonnet 4.5 Retires: I Counted Callers From the Usage CSV, Not From grep
claude-sonnet-4-5 retires on November 30. grep only shows what is written in code. Here is a single script that cross-checks model IDs in your code against the Console's Usage CSV, with the results from running it.
I Added the allow Rule and the Prompt Still Appears — Reading Six Layers from /permissions
When an allow rule is in your settings and the same approval prompt keeps coming back, something else decided first. Starting from what /permissions shows, here are six layers you can verify against the official permissions docs: ask and deny precedence, where settings.local.json is read, Cowork's shell tool, and more.
The Morning WS Came Back Empty in a Scheduled Task, and I Learned There Were Two Shells
Step 1 of a scheduled task left my workspace variable empty. The cause was a second shell. Here is what the same probe returned in both, and a tool_result guard that turns the silence into an error.
When a Scheduled Task Keeps Saying SUCCEEDED but Produces Nothing, Check Outbound Traffic in the First Minute
The run history is green, but the output file is still yesterday's. A short probe and a freshness check that tell you in the first minute whether outbound calls are being refused with a 403 on CONNECT.
The Token-in-URL Way of Authenticating git Stopped Working in One Scheduled Task
A git clone stopped with 'could not read Username'. Two ways of putting a token in the URL behaved differently, and this is how I ended up on askpass.
Sending 40 Rows From Make to the Claude API Stops at Row 14 — Avoiding the 429 With One Subtraction
Why a no-code automation that sends spreadsheet rows to the Claude API one by one hits a 429 partway through, and how to fix it. Seven spacing strategies tested on a mock bucket, a formula for the Sleep delay, and settings that stop failed rows from vanishing.
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