The gitea-axi arm was the only shell arm handed no credentials: the
runner set only PATH, so the agent had to reverse-engineer the tea-login
system — guessing a profile name and hunting for a config file — before
any real work, burning ~4 turns per task. Since turns drive cache-read,
the benchmark's dominant cost metric, this scaffolding gap alone inflated
gitea-axi's cost-equivalent tokens above every other arm.
Hand the arm its host and token through gitea-axi's own env interface
(GITEA_AXI_API_URL / GITEA_AXI_TOKEN), the symmetric counterpart to the
gitea-mcp server's GITEA_HOST / GITEA_ACCESS_TOKEN env: both name the
same two facts, and both still leave the agent to name the repository per
call. A shell arm now carries a credential env (empty for tea and
raw-api, which need none), merged under PATH in the driver.
Also strengthen SKILL.md so a cold agent targets and authenticates on the
first call: an explicit "Targeting and authentication" section replaces
the buried, optional-looking one-liner, spelling out that outside a
checkout `-R OWNER/NAME` plus the environment's token is all that is
needed — do not go hunting for a config file or login profile.
Verified live: create-memory-leak-issue dropped from 10 turns to 3 and
its cache-read fell ~3.8x, with the auth flailing gone from the transcript.
Add bench/arm.ts, the per-arm scaffolding that produces the single arm
definition the runner consumes. Every arm shares an identical task-agnostic
base prompt and the same repository coordinates and token; each arm then
receives a minimal, symmetric bootstrap.
The deliberate asymmetries follow the shipped products: the gitea-axi arm
embeds the bundled Agent Skill (its body, charging its ambient cost to
gitea-axi); the tea and raw-api arms get a one-line native-discovery pointer;
the gitea-mcp arm runs with the shell disabled and only the MCP server
attached, its dispatcher schemas loading eagerly. Shell arms' PATH and guard
come from bench/guard.ts.
