Jeremy Rose
b389b950e1
## Summary Turn diff updates repeatedly rendered and serialized the entire accumulated diff after every `apply_patch`. The event path also rendered once before updating the tracker solely to test whether a diff existed. In production feedback CODEX-20PW, 2,589 patches across 72 paths produced 401 notifications totaling 441 MB, with the hottest paths patched 518 and 495 times. This change: - replaces the pre-update render with a cheap cached-state check - caches each rendered file diff by path and content revision, so an update only invokes Myers for affected paths - caches the deterministic aggregate diff so event emission and turn completion reuse it without recomputation - preserves invalidation and net-zero clear notifications - applies a 100 ms per-file `similar` timeout; ordinary files complete far below this threshold, while pathological rewrites fall back to a coarse unified hunk that still represents the exact final contents The 100 ms deadline bounds synchronous tool-completion latency while leaving substantial headroom for normal diffs. The regression test applies the fallback diff through the repository's patch parser and verifies byte-for-byte final contents. ## Validation - `cargo test -p codex-core turn_diff_tracker::tests` (14 passed) - `cargo test -p codex-core tools::events::tests` (4 passed) - `just fix -p codex-core` - `just fmt` Focused coverage verifies that 42 updates across two files perform 42 file renders rather than repeatedly rendering the accumulated set, unchanged paths are not re-diffed, clear events remain correct, and a 48,000-line near-total rewrite returns promptly and applies to the exact expected result. The full `codex-core` suite was not used as the final gate because an unrelated existing multi-agent test hit a stack overflow when run during investigation. ## Bug context - Sentry feedback: CODEX-20PW - Correlation IDs: `019eb2a9-13d2-74e0-b690-27ee224ffb6d`, `019e9ad7-09c3-7cb2-b728-ee3acba103ab`
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
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.