Handle HOME/WORKSPACE_DIR fallbacks in agynd (per 2026-04-24 spec)

[rowan-stein]

User request / architecture change

Architecture change doc: agynio/architecture → changes/2026-04-24-home-workspace-env.md.

• Agents Orchestrator should not inject or reserve HOME / WORKSPACE_DIR.
• Agent-specific fallbacks live in agynd.

Specification

1) Codex HOME fallback

If HOME is empty for the Codex subprocess environment, set HOME=/tmp before spawning (Codex resolves ~/.codex against HOME and needs a writable path).

• This fallback is Codex-specific.

2) Init scripts workdir fallback

Run init scripts with working directory:

• WORKSPACE_DIR when that variable is defined, otherwise
• /tmp

(Implementation hint: internal/config/config.go currently defaults WORKSPACE_DIR to /workspace when unset; this should become /tmp so init scripts run in /tmp by default.)

Acceptance criteria

• go test ./... passes.
• When WORKSPACE_DIR is unset, init scripts run in /tmp.
• When HOME is unset, Codex still starts (via HOME=/tmp fallback).

[rowan-stein]

Follow-up blocker discovered while rolling out the HOME/WORKSPACE changes:

After agents-orchestrator PR #158 stops injecting/mounting HOME+WORKSPACE, e2e now reaches the agent but the AGN runtime exits when trying to call token counting:

daemon exited: rpc error -32603: count tokens: rpc error: code = Unavailable desc = name resolver error: produced zero addresses

Root cause: agn defaults token-counting address to token-counting:50051, but in our stacks the service lives in the platform namespace, so the short name isn’t resolvable from the workload namespace.

Required fix in agynd:

• When generating the agn config (internal/daemon/agnconfig.go), write token_counting.address to a resolvable value (preferably derived from AGYN_API_ADDRESS, with env override if present).

Once merged/released, we’ll bump agent-init-agn + e2e defaults and re-run agents-orchestrator PR #158 e2e.