Michael Bolin
01f89c8c59
## Why PR #29494 made context-window IDs visible to the model by wrapping the token-budget window payload in `<context_window>`, but rollout JSONL consumers still could not see the initial window identity by tailing the session file. Compacted rollout items carry window IDs only after compaction has happened, so a session with no compaction had no durable JSONL record for window 0. This change gives tailing consumers a stable initial-window record at session creation time. ## What Changed - Added `session_meta.context_window.window_id` for the initial context-window identity. - `CreateThreadParams` now requires `initial_window_id: String`, so thread-store callers cannot accidentally create new threads without window-0 metadata. - Live thread creation derives the persisted initial window ID from the same `AutoCompactWindowIds` used to initialize `SessionState`, keeping runtime state and JSONL metadata aligned. - Rollout reconstruction uses `session_meta.context_window.window_id` as the initial-window fallback and derives `window_number = 0`, `first_window_id = window_id`, and `previous_window_id = None` internally. - Fork reconstruction intentionally uses the same rollout reconstruction path; consumers that need to distinguish copied initial-window metadata can use the rollout `thread_id`. - Legacy compactions without `window_number` still use compaction-count fallback accounting instead of being reset to window 0 by the initial-window fallback. - Compacted rollout metadata still takes precedence once compaction records exist, preserving the richer chain fields there. ## JSONL Shape Real rollout JSONL is one object per line. This example is expanded for readability, but shows the new initial `session_meta.context_window` record followed by the existing compacted rollout item shape that also carries window IDs: ```jsonl { "timestamp": "2026-06-22T12:00:00.000Z", "type": "session_meta", "payload": { "session_id": "<THREAD_ID>", "id": "<THREAD_ID>", "timestamp": "2026-06-22T12:00:00.000Z", "cwd": "/repo", "originator": "codex", "cli_version": "0.0.0", "source": "cli", "model_provider": "<MODEL_PROVIDER>", "context_window": { "window_id": "<INITIAL_WINDOW_ID>" } } } ... { "timestamp": "2026-06-22T12:34:56.000Z", "type": "compacted", "payload": { "message": "<COMPACTION_SUMMARY>", "replacement_history": [ "..." ], "window_number": 1, "first_window_id": "<INITIAL_WINDOW_ID>", "previous_window_id": "<INITIAL_WINDOW_ID>", "window_id": "<NEXT_WINDOW_ID>" } } ``` The nested `context_window` object is intentional: it gives rollout consumers a stable namespace for context-window metadata while only writing the non-derivable initial `window_id`. For the initial window, `window_number`, `first_window_id`, and `previous_window_id` are derived internally instead of being written to the rollout. ## Verification - `just test -p codex-protocol` - `just test -p codex-rollout recorder_materializes_on_flush_with_pending_items` - `just test -p codex-core reconstruct_history` - `just test -p codex-core record_initial_history_reconstructs_forked_transcript` - `just test -p codex-thread-store` - `just test -p codex-state` - `just test -p codex-app-server thread_read_returns_summary_without_turns` - `just test -p codex-rollout persistence_metrics`
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
Wine-exec integration tests
On x86-64 Linux, run the shared suite against the Windows exec server with
bazel test //codex-rs/core:core-all-wine-exec-test.
Local execution targets the host OS, Docker targets Linux, and Wine exec targets Windows. Choose the skip macro by what the test depends on:
skip_if_target_windows!: Windows target behavior.skip_if_host_windows!: Windows host constraints.skip_if_remote!: Local-only test behavior.skip_if_no_remote_env!: Remote-only test behavior.skip_if_wine_exec!: Wine-specific runner debt.
Dependencies
Note that codex-core makes some assumptions about certain helper utilities being available in the environment. Currently, this support matrix is:
macOS
Expects /usr/bin/sandbox-exec to be present.
When using the workspace-write sandbox policy, the Seatbelt profile allows
writes under the configured writable roots while keeping .git (directory or
pointer file), the resolved gitdir: target, and .codex read-only.
Network access and filesystem read/write roots are controlled by
SandboxPolicy. Seatbelt consumes the resolved policy and enforces it.
Seatbelt also keeps the legacy default preferences read access
(user-preference-read) needed for cfprefs-backed macOS behavior.
Linux
Expects the binary containing codex-core to run the equivalent of codex sandbox when arg0 is codex-linux-sandbox. See the codex-arg0 crate for details.
Legacy SandboxPolicy / sandbox_mode configs are still supported on Linux.
They can continue to use the legacy Landlock path when the split filesystem
policy is sandbox-equivalent to the legacy model after cwd resolution.
Split filesystem policies that need direct FileSystemSandboxPolicy
enforcement, such as read-only or denied carveouts under a broader writable
root, automatically route through bubblewrap. The legacy Landlock path is used
only when the split filesystem policy round-trips through the legacy
SandboxPolicy model without changing semantics. That includes overlapping
cases like /repo = write, /repo/a = none, /repo/a/b = write, where the
more specific writable child must reopen under a denied parent.
The Linux sandbox helper prefers the first bwrap found on PATH outside the
current working directory whenever it is available. If bwrap is present but
too old to support --argv0, the helper keeps using system bubblewrap and
switches to a no---argv0 compatibility path for the inner re-exec. If
bwrap is missing, it falls back to the bundled codex-resources/bwrap
binary shipped with Codex and Codex surfaces a startup warning through its
normal notification path instead of printing directly from the sandbox helper.
Codex also surfaces a startup warning when bubblewrap cannot create user
namespaces. WSL2 uses the normal Linux bubblewrap path. WSL1 is not supported
for bubblewrap sandboxing because it cannot create the required user
namespaces, so Codex rejects sandboxed shell commands that would enter the
bubblewrap path before invoking bwrap.
Windows
Legacy SandboxPolicy / sandbox_mode configs are still supported on
Windows. Legacy read-only and workspace-write policies imply full
filesystem read access; exact readable roots are represented by split
filesystem policies instead.
The elevated Windows sandbox also supports:
- legacy
ReadOnlyandWorkspaceWritebehavior - split filesystem policies that need exact readable roots, exact writable roots, or extra read-only carveouts under writable roots
- backend-managed system read roots required for basic execution, such as
C:\Windows,C:\Program Files,C:\Program Files (x86), andC:\ProgramData, when a split filesystem policy requests platform defaults
The unelevated restricted-token backend still supports the legacy full-read
Windows model for legacy ReadOnly and WorkspaceWrite behavior. It also
supports a narrow split-filesystem subset: full-read split policies whose
writable roots still match the legacy WorkspaceWrite root set, but add extra
read-only carveouts under those writable roots.
New [permissions] / split filesystem policies remain supported on Windows
only when they can be enforced directly by the selected Windows backend or
round-trip through the legacy SandboxPolicy model without changing semantics.
Policies that would require direct explicit unreadable carveouts (none) or
reopened writable descendants under read-only carveouts still fail closed
instead of running with weaker enforcement.
All Platforms
Expects the binary containing codex-core to simulate the virtual
apply_patch CLI when arg1 is --codex-run-as-apply-patch. See the
codex-arg0 crate for details.