The checked-in plugins/codex-base tree is the distributable plugin. Portable
third-party skills are generated from pinned inputs. src/improve is the
first-party Codex adaptation of Improve; its scripts, config, schemas, and
references are copied into the generated Improve skill. The current execution
contract version is declared in src/improve/SKILL.md.
src/docs-routing is the canonical first-party documentation-routing skill.
src/benchmark-checklist, src/blast-radius, and
src/deprecation-and-migration hold concise local MIT adaptations.
nix/skills.nix owns its deterministic construction alongside the other skills. The sync command
materializes that Nix output into the checked-in plugin and check mode compares
without writing. Both plugin and Home Manager consumers therefore use the same
files.
The portable plugin owns anonymous HTTP defaults for Context7 in .mcp.json; it contains no authenticated server or credentials.
Home Manager retains its local anonymous Context7 adapter and optional
per-user context7_auth adapter. Native Codex same-name configuration provides
the override boundary. Context7 connections receive only focused
public lookup terms, never private or secret content.
nix/packages.nix packages the default Codex CLI and Code Mode Host, Playwright CLI,
and codex-improve and codex-doctor wrappers that accept a Codex package. nix/home-manager.nix owns the full Linux runtime:
config overlay, MCP wrappers, global instructions, rules, packages, and direct
unnamespaced skill links. Its package option installs one CLI package and passes
that package's absolute bin/codex path to both helpers. The Improve wrapper
passes the path through the launcher to its worker, so launcher PATH changes
cannot select another CLI. The portable plugin still resolves codex from the
host PATH. Home Manager intentionally renders no Improve profile files.
The desktop SSH client starts Codex App Server on the remote host. That process can serve multiple chats, so installing a new binary and starting a new chat does not necessarily replace it. Runtime updates and guidance reloads follow the reload instructions; the desktop client and remote execution environment are separate installations.
Home Manager writes the base AGENTS.md first and appends nonempty
programs.codexBase.extraInstructions after a blank line to the user's global
guidance, which Codex loads for every project. The base stores persistent
per-user Git, Nix, secret-handling, evidence, and working preferences;
environment-specific policy such as proxy handling belongs in a consuming
module's extra instructions. The portable plugin does not install global
guidance. Executor prompts retain runner-local scope, checks, STOP, and handoff
constraints. Codex Base has no model-index or per-model global guidance files,
and its ordinary runtime default remains Sol with medium reasoning.
Native context-management eligibility depends on callable tools in the live session and server capability for the signed-in account. In the desktop app, that task is a Codex chat under a project; entering Plan Mode or invoking Improve in an existing chat does not start another session. Codex Base therefore keeps Sol as its ordinary default. Formal Improve planning requires a session that actually exposes context management and structured questions. Astra is an explicit choice for difficult planning; its name is not capability evidence.
In the CLI, ordinary /model selection changes the current chat and attempts
to persist defaults. /new uses effective defaults plus explicit launch
settings, rather than simply copying the current chat's model. Codex 0.155.1
preserves a launch-model override across those /new chats. A user who keeps
Sol as the persistent default can start a one-off Astra invocation with
codex -m gpt-6-astra; Codex Base does not ship an Astra runtime profile.
The configuration guide records the scope
distinctions and pinned source evidence.
Formal Improve planning uses built-in Plan Mode only when the live session exposes callable native context management and structured questions. It produces one complete replacement in chat and creates no plan, questionnaire, handoff, or temporary file. A later authorized writable phase may persist that result. Implementation, audits, and routine lifecycle bookkeeping remain available in Default Mode without starting a new planning workflow.
The historical prompt comparison for Codex 0.153.4 is limited to the public
templates in models-manager/models.json at revision
3d2ee51ca2d5db578f328aa75e20aa22c0197c9a: Sol, Terra, and Luna share that
public base/template content, while Astra differs. It does not describe the
current release pin or undisclosed server-side instructions, and Codex Base
does not copy those model prompts.
Improve reads the selected role from src/improve/config/roles.json and stores
its effective settings with each execution. It never looks up a Codex profile.
Improve .17 uses the public codex-improve coordinator. A reviewed plan
selects economy (Luna/low), standard (Sol 6.1/medium), or deep (Sol 6.1/xhigh). Scout
uses Luna/high; the comprehensive reviewer uses Sol 6.1/high. The coordinator
reads the launcher and probes from the plan, snapshots the selected role, and
runs one model call. It does not probe quota, switch models, or replay failures.
The Nix closure supplies Python 3.11 or newer, Git, Codex, and Worktrunk. A
portable plugin install requires these host commands. Worktrunk manages
worktrees; Git owns exact candidate and checkpoint operations. The plugin
changes neither the user's main model nor native Codex configuration.