fix: active community rail, Codex nest isolation, ecosystem docs

[Chessing234]

Summary

• Active community shows a rail pill + ring even with custom icons
• Managed Codex agents use CODEX_HOME=~/.buzz/.codex (auth handed off)
• Ecosystem docs point at buzz-releases and note legacy sprout-* names

Test plan

• just ci
• Join 2+ communities with custom icons → active one is obvious in the rail
• Start a Codex agent → sessions land under ~/.buzz/.codex, not personal Codex Remote
• Skim AGENTS.md ecosystem table for the rename note

Closes #2570
Closes #2660
Closes #2557

Made with Cursor

[Dirtywater97]

This PR has been open without review since 24 Jul. Adding a fresh reproduction in case it helps prioritise: #2660 (comment)

Summary — on Windows 11 with codex-cli 0.145.0 and codex-acp 1.1.7, managed agents wrote 72 rollout files across two separate Codex homes: 33 into the user's personal ~/.codex, and 39 into a different application's private CODEX_HOME, because Buzz inherits whatever value is in the environment at spawn.

One implementation note for this change: because the observed failure mode is an inherited CODEX_HOME rather than an absent one, the nest home needs to be set unconditionally at spawn. Defaulting only when the variable is unset would still leak in the cross-application case above.

[Dirtywater97]

Withdrawing the implementation note in my comment above.

I claimed the failure mode was an inherited CODEX_HOME and that this PR therefore needed to set the variable unconditionally rather than defaulting when unset. That was based on seeing managed-agent sessions in two directories.

Those directories turned out to be hardlinked on the machine I tested — same inodes, same content, one set of files. There is no evidence of an inherited CODEX_HOME here, and no cross-application write. Full correction: #2660 (comment)

So the nest-home approach in this PR is sound as written; please ignore my suggested change.

The underlying report is unaffected: 39 managed-agent rollout files landed in the user's personal ~/.codex on Windows 11 (codex-cli 0.145.0, codex-acp 1.1.7), interleaved with their own sessions. This PR would have prevented that. It has been open without review since 24 Jul.

[Chessing234]

thanks for the correction and the fresh repro — nest home stays as written

[Chessing234]

@tlongwell-block @wesbillman @wpfleger96 mind taking a look when you get a chance?

[Chessing234]

closing this — three unrelated concerns in one branch, and it now conflicts with main. i'll bring back the codex nest isolation on its own if it's still wanted