Drop the quotes on a heredoc and the prices in your log quietly change
An unquoted heredoc runs the variables and backticks inside its body. Here are the four ways my log got rewritten, how the three quoting forms compare, a safe placeholder-and-sed pattern, and a small script for auditing what you already have.
Half of My Scheduled Runs Vanished Without a Single Error
A batch job set to run twice a day was only firing once. No errors, no failure alerts. Here is how to expand your own schedule, count expected runs, and reconcile them against execution records to catch silent misses.
Don't let your verification script's full output flow back through a hook
The check was working the whole time. The conversation was what ran out of room. Measured side by side: one scan of 833 files returns 58 bytes, another returns 42KB. Here is how to put an output budget on your hooks.
Trusting the allow rules in your repo, or moving them to the environment
On disposable machines, the permissions.allow rules committed to your repo are dropped while the workspace waits to be trusted. Here is what gets dropped and what survives on 2.1.246, where each kind of rule belongs, and a preflight that catches the gap before a run starts.
A One-Letter Typo in settings.json Is Ignored Without a Single Warning
I diffed claude doctor output between a settings.json with misspelled keys and a correct one. There was no difference at all. Here is what actually gets validated, what slips through, and a small check that catches typos before they cost you a day.
One Space in a Folder Name Turned 80 Checks Into Zero
An inspection loop reported 80 files checked and 0 readable. The files were fine. Here is how word splitting turns path fragments into real directories, measured side by side, plus the count assertion I now put in front of every delete-heavy batch.
Not Every Unreachable Connector Means the Same Thing in an Unattended Run
When an unattended task cannot reach a connector, the cause splits into three states: still connecting, unauthenticated, or genuinely absent. Each demands the opposite response. Here is the resolver that tells them apart.
Handing a long job to another session — and the completion marker for when the notification never arrives
How to use notify_when_idle to hear when another Claude Code session finishes, and a small completion marker that keeps you from waiting forever when the notification is dropped.
One Transient 401 Replaced My Long-Lived Token — Giving Credentials a Provenance Field
A shared credential file can lose its long-lived token to a single transient 401. I injected exactly one 401 into a 24-worker fleet, measured the blast radius, and compared a provenance guard against full isolation.
Passing the Request, Not the Secret — Where Sandbox Credential Masking Works and Where Substitution Breaks
Claude Code's sandbox credential masking lets processes read sentinel values while a proxy swaps in the real secret at send time. I rebuilt it as a minimal proxy and measured which auth schemes survive the swap, which break, and what happens when the secret rides in the body.
Tightening Filesystem Isolation Separately from the Network — Collect the Paths, Then Squeeze the Write Surface
Claude Code v2.1.216 lets you control filesystem isolation independently from network isolation. Before tightening anything, I traced what a real job actually touches, split reads from writes, and measured how stable the path set is across repeated runs. The numbers changed how I wrote the allowlist.
Existence Checks Pass, Writes Fail — Probing Capabilities Before an Unattended Run
A directory existing and a directory being writable are two different facts. Measured results from five broken-environment cases, and a capability-probe preflight for unattended Claude Code runs.