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The MCP Server I Thought I Killed Was Still Holding the Port: 84 Teardown Trials
Closing a session should stop the MCP servers it started. Across 84 trials of four teardown strategies, a process-group SIGTERM left zero orphans — until the child called setsid, at which point it left 100%. Includes a full descendant-sweep implementation.
I Asked the Agent to Pick Tests From My Diff and It Said "None" Nine Times Out of Ten
Change-based test selection returned zero tests for most edits. Measuring how far an import graph actually reaches across three repositories, and rebuilding the selection contract around it.
Seven Characters Don't Only Point at Commits — Measuring When Your Agent's Recorded Hashes Stop Resolving
Short commit hashes recorded by an agent quietly stop resolving as a repository grows. Measuring where ambiguity begins, fixing the recording side, and building a batch verification gate.
Reading the Same History in 38 Seconds — or 0.4: Handing a Read-Only .git to Your Agent
Antigravity CLI 1.1.10 lets the sandbox read .git without write access. I built a per-session history summary two ways, measured a roughly 100x speed gap, traced it to process spawn cost, and added a guard for shallow clones that silently corrupt the numbers.
Startup Dropped to 3ms, and the First Turn Saw Zero Tools
Non-blocking MCP loading cut startup from 2,907ms to 3ms. The wait did not disappear — it moved into the first turn. Here is where it went, measured, plus a readiness gate that waits only for what a turn actually needs.
I Measured Before Writing a Number: MCP Connect and Tool Calls Differed by 486x
Antigravity 2.4.3 lets you set a timeout per MCP server. To find a defensible number I built a stdio server, measured each boundary separately, and found why a single value cannot cover both.
I Copied the Same agent.md Into Another Repo and It Quietly Did a Different Job
CLI 1.1.6 lets you carry agent definitions around as files. I dropped one definition into eight repos, built a preflight that resolves its declared capabilities before the agent runs, and measured it against a naive checker.
The Date Column Was the Most Expensive Part of My Sales CSV — Measuring What Attachments Really Cost
2.4.3 lets you attach .json, .md, and .csv files directly. I rendered the same table eight ways, priced every column in tokens, and boiled it down to a 1,062-token digest. Every number here came from a run on my own machine.
The Flaky Hook Started Failing Every Time — Migrating to Declarative Sessions in the Antigravity SDK
Registering hooks after session init is gone, replaced by declaration at session creation. Here is what happened when I moved four agent definitions across, plus the harness I used to measure ordering non-determinism over 2,000 runs.
Half My Tasks Went to Pro — and So Did Only 61% of the Tokens
A singular model setting became a models collection, which means routing across models is now something you define yourself. Here is how I re-measured a task-type routing rule against the actual context-size distribution of 67 tasks in my own repository.
A Typo in agent.md Quietly Widened My Permissions — Writing a Strict Frontmatter Lint
Misspelled keys in agent.md frontmatter do not raise errors. They fall back to defaults, and for permission fields that fallback points the wrong way. Here is the failure I hit, the lint I wrote to catch it, and what the measurements showed.
Three Tools Named read_file: Catching MCP Name Collisions Before Startup
Bundle enough MCP servers and tool names collide quietly. Here is what a real 5-server, 21-tool setup measured at 43% collision, plus a Python preflight that catches them before startup and assigns deterministic aliases.