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, why static clues cannot predict the worst of them, and a capability-probe preflight for unattended Claude Code runs.
Resuming After a Budget Stop: What 36 Enumerated Stop Points Taught Me
A budget cap that halts a headless run is neither success nor failure. I enumerated every stop point, measured resume integrity and total spend, and ended up changing what the cap applies to.
Whose Environment Expands That Variable? Fingerprinting Your Effective Managed MCP Policy
Variable references in the Managed MCP allowlist and denylist now resolve from the startup environment and the managed-settings env block. I rebuilt both resolution orders locally to see where verdicts diverge, then wrote a preflight check that reduces the effective policy to a comparable fingerprint.
Locking down Claude Code sandbox egress with strictAllowlist
Tightening automation egress with strictAllowlist in Claude Code v2.1.219, plus measured failure timings that tell a policy deny from DNS and real outages, and three defects that made my own recon scripts return nothing.
A Committed Symlink That Points Outside the Worktree — Auditing Repos Before You Let AI Spin Up Parallel Trees
Claude Code 2.1.212 fixed a bug where a committed symlink under .claude/worktrees could be followed during worktree creation and write outside the repo. The patch closes the following side. Here is an audit script for the committed side, plus a quarantine workflow.
I Stopped the Headless Claude Code Job, but the Build Kept Running — Designing Teardown Around exit 143
In headless mode, a SIGTERM received while Claude Code was mid-Bash used to orphan the command's process tree. The 2.1.212 fix changes that to a clean exit 143. Here is how to redesign your supervisor and cleanup around that contract.
Branch with /fork, Delegate with /subtask — Two Commands That Traded Jobs
In Claude Code 2.1.212, /fork now clones your conversation into a background session, and in-session subagents moved to /subtask. Here is how I decide between them, and the budgets worth setting before you start branching freely.
The String I Approved Wasn't the String I Read — Testing a Relayed Permission Prompt with Deceptive Characters
I pushed bidi overrides and zero-width characters through my own approval relay. NFKC normalization caught 0%. Here is why, and the implementation that catches 100% with zero false positives.
My Nightly Subagents Ran, and I Couldn't Retrace Them — Trimming the Logs That --forward-subagent-text Unleashed
Subagent text and thinking can now flow into stream-json output, and unattended log volume climbs sharply with it. Here are measured numbers, a three-tier retention filter that keeps only what postmortems need, and a correlation ID design that survives missing fields.
It Worked on My Machine, but Nobody Could Trigger It — Four Assumptions I Stripped Out of a Cowork Plugin
I bundled four working automation skills into a plugin and shared it. Only one of them ever fired. Here is how I measured skill trigger rate, and the four assumptions — vocabulary, paths, connections, and naming — I had to strip out before it was portable.
The Morning My Table Ended in "… 2,847 more rows" — Separating Render Caps from Token Cost in Tool Output
Claude Code 2.1.209 caps markdown tables at 200 rows plus a remainder count. Only the rendering is capped — the model still receives every row. Here is how to measure the gap and redesign tool output around aggregates.
Answering auto mode's confirmation prompts in headless runs — a deny-by-default permission-prompt-tool
auto mode's confirmation step is a friend when you're at the keyboard, but in an unattended midnight run it becomes the reason a job sits waiting until morning. Here is how I catch those prompts with permission-prompt-tool, decide deny-by-default, and log every ruling — with working code.