Tracking Multi-Step Work in Claude Code Now That the Todo Tools Are Off by Default
Since Claude Code v2.1.233, TodoWrite and the Task tools are left out on the newer models. Here are the three branches to check before you set the opt-in variable, the PostToolUse ledger I put in their place, and the measured point where that ledger quietly corrupts under parallel agents.
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.
The 400-Character Preview That Was Still Holding On to a Megabyte
Truncating tool output in your own MCP server does not free the original. Node's sliced strings keep the parent alive. Here is the measured 13-character boundary, which flattening tricks actually work, and a heap-snapshot audit script that counts the retained parents for you.
You Added a Second Working Root — Now Ask How Far Your Ignore Rules and Deny Patterns Actually Reach
Adding a working root mid-session does not carry your ignore rules or deny patterns with it. Measured evidence from git check-ignore and a three-way matcher comparison, plus the scope-delta audit script I now run from the DirectoryAdded hook.
The MCP Server Connects Fine and Still Hands Back Zero Tools — Catching Silent Capability Drift with a Tool Manifest Diff
A missing credential does not break the MCP handshake. initialize succeeds, tools/list succeeds, and the array comes back empty. Here is the measured behaviour, and a preflight that locks the expected tool surface and fails closed before the agent ever starts.
The Line That Disappears at 100K: Measuring What Tool-Output Spill Actually Keeps
When agent tool output passes 100,000 characters, the full text spills to a file and the model sees only a head-truncated preview. Here are measured survival rates from a real repository, and the output envelope I built to push decision-relevant lines to the front.
Swapping Agent Config Per Session From One Shared Definition
A design pattern for running one base Managed Agent and overriding its model, prompt, tools, MCP servers, and skills per session with agent_with_overrides — with a validated factory and the operational traps I hit along the way.
I Could No Longer Remember What I'd Changed in Auto Mode — Where claude auto-mode reset Fits In
Running nightly automation for weeks, I kept nudging my auto-mode settings one at a time. One morning a small oddity made me realize I could not recall what I had changed. Here is how I rebuilt my configuration around claude auto-mode reset as a known-good baseline, from a solo developer's field notes.
Your Overnight Session Wakes Up at 3GB — Four Places Memory Piles Up, and How to Tell Them Apart
The Claude Code process I left running overnight had grown to 3.4GB of resident memory by morning. Here are the four accumulation sources closed in 2.1.209, how to separate what's left in your own setup by sampling RSS slope, and a watchdog pattern that folds a session before it hurts.
An Empty Variable and rm -rf: How Claude Code's Auto Mode Preflight Saved My Late-Night Cleanup
An empty variable nearly turned rm -rf into a wide delete. Why set -u lets an empty string pass, and the cleanup script I rebuilt with dry run as the default.
Tightening Tool Schemas From the Arguments You See in Production
Record the arguments Claude actually passes to your tools in production, then use that distribution to add enums and patterns back into your JSON Schema. With logging code and before/after numbers.