> **Draft / open question for maintainers.** The failure mode this fixes
is narrow — a new-Zed-created container exists under the `name`-field
project while a CLI-derivation tool (`@devcontainers/cli`, VS Code)
operates on the same folder (the container persists in Docker, so the
originating Zed session doesn't need to still be open). See issue #54255
failure mode 3 and the fixture's step 6.
>
> I'd like to pose this as a question rather than a claim: is matching
`@devcontainers/cli`'s `getProjectName` precedence something the project
wants to take on, given the narrowness of the bug? I wrote this
implementation mostly as a way to explore what parity would actually
cost — happy to close it if you'd rather leave it as-is, or pare it down
(e.g. just rule 4) if a partial match is preferable.
>
> The broader value beyond this specific bug: devcontainer impls
agreeing on the same project name means containers created by Zed, the
devcontainer CLI, and VS Code are interchangeable for the same folder,
which feels worth it to me — but you know the project's priorities
better.
>
> Folds in #54068 (detection) — closing that PR unmerged; its
`MultipleMatchingContainers` error lands here.
Self-Review Checklist:
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable
Closes#54255
## Summary
**Match `@devcontainers/cli`'s full `getProjectName` precedence.**
Replaces `safe_id_lower(devcontainer.json's name)` with the five-step
chain the reference CLI walks (see [`src/spec-node/dockerCompose.ts` in
devcontainers/cli](https://github.com/devcontainers/cli/blob/main/src/spec-node/dockerCompose.ts)):
1. `COMPOSE_PROJECT_NAME` from the local environment.
2. `COMPOSE_PROJECT_NAME=` in the workspace `.env` file.
3. Top-level `name:` on the merged compose config, when at least one
fragment declared it explicitly.
4. `${workspaceFolderBasename}_devcontainer` — only when the first
compose file's directory is `<workspace>/.devcontainer/`.
5. Otherwise, the plain basename of the first compose file's directory
(no suffix).
The old Zed implementation diverged at every one of those inputs: any
user setting `COMPOSE_PROJECT_NAME`, shipping a `.env` with one,
declaring a top-level compose `name:`, or pointing `dockerComposeFile`
outside `.devcontainer/` (e.g. `"../docker-compose.yml"`) got a
different project namespace than the CLI and VS Code, producing two
compose projects for the same folder.
Adds a small `sanitize_compose_project_name()` helper implementing the
CLI's rules (lowercase + strip `[^-_a-z0-9]`) — notably preserving
hyphens, which `safe_id_lower` would have replaced with underscores.
Adds two helpers used by the precedence walk:
- `parse_dotenv_compose_project_name` — line scan extracting
`COMPOSE_PROJECT_NAME=…` from the workspace `.env`, matching the subset
the CLI's regex dotenv reader recognizes.
- `compose_fragment_declares_name` — parses each compose fragment with
`yaml-rust2` (already a transitive workspace dep; slated to become a
direct dep via #53922) and checks for a `name` key on the root mapping
(block, quoted, or flow style all work), matching the CLI's own
`yaml.load`. `docker compose config` always injects `name: devcontainer`
into its merged output when no fragment declared one, so rule 3 needs to
distinguish the user-provided case from the injected default — this
helper supplies that signal. On YAML parse failure it returns "not
declared" (rule 4 applies), matching the CLI's fallback.
`project_name()` becomes async and fallible (`async fn
project_name(&self) -> Result<String, DevContainerError>`) so it can
load the `.env` file and each compose fragment via `self.fs.load`. Four
call sites now `.await?` the derivation. Real I/O errors on the `.env`
read propagate as `FilesystemError` (matching the CLI's narrow
`ENOENT`/`EISDIR` swallow); fragment-rescan read errors are logged and
skipped (matching the CLI's broader try/catch over its fragment read +
parse).
The `name` field is still used as the features image-tag prefix
(`generate_features_image_tag`); only the compose project namespace is
decoupled from it.
**Duplicate-container detection (from #54068).** When
`check_for_existing_container`'s label-based lookup returns more than
one match, propagate `MultipleMatchingContainers(ids)` with instructions
to clean up the stale one(s). This covers the mixed-version upgrade edge
case where a pre-fix Zed left a container under the legacy project name
alongside a CLI-style one — transparent to users in the common case (one
tool, one container), explicit error when two legacy siblings need
manual cleanup.
## Why
Full write-up with verified fixtures and captured output: #54255.
Three failure modes from the same root cause, all resolved by this
change:
1. **Interop** — opening a folder in both Zed and `devcontainer up` (or
Zed and VS Code) creates two compose projects with identical
`devcontainer.local_folder` + `devcontainer.config_file` labels,
breaking the spec's uniqueness invariant.
2. **Cross-worktree silent db/volume reuse** — if multiple git worktrees
share a `devcontainer.json` with the same `name`, Zed uses the same
compose project for all of them; Compose reuses stateful siblings (db,
cache, localstack) by config-hash, so worktree B silently inherits
worktree A's database. Fixture + captured output:
[antont/zed-devcontainer-db-share-repro](https://github.com/antont/zed-devcontainer-db-share-repro).
3. **Mixed-version Zed sessions** — the Rust impl landed in stable
v0.232.2 (2026-04-15, #52338). Older Zed (≤v0.231.x) shelled out to
`@devcontainers/cli` so it used the reference derivation. The collision
shows up when a new-Zed-created container exists under the name-field
project while a CLI-derivation tool (old Zed, `devcontainer up`, VS
Code) operates on the same folder.
## Migration / compatibility
Existing Zed-created containers (under the old `safe_id_lower(name)`
project) continue to be found via `check_for_existing_container`'s
label-based lookup — they're looked up by `devcontainer.local_folder` +
`devcontainer.config_file`, not by project name. A user with duplicate
legacy containers from a prior Zed session sees
`MultipleMatchingContainers` with cleanup instructions.
## Revision — 2026-04-22
Revised per @KyleBarton review on the prior version:
- Swapped the YAML parser from `serde_yaml_ng` to `yaml-rust2` (already
transitive via `tree-sitter-yaml`; net reduction of one direct workspace
dep; also what #53922 will pull in).
- Dropped the mixed-version tiebreak (`pick_canonical_container`) and
its `com.docker.compose.project` serde label. The edge case it covered
is transient enough to address via the explicit
`MultipleMatchingContainers` error rather than permanent tiebreaking
code.
- Folded #54068's detection commit into this PR; #54068 closed unmerged.
- Rebased onto `main`.
## Test plan
- [x] `cargo test -p dev_container --lib` — 89 passed, including:
- `sanitize_compose_project_name_matches_cli_rules`
- `--project-name` assertion added to
`test_spawns_devcontainer_with_docker_compose`
- `check_for_existing_container_errors_when_multiple_match`
- `derive_project_name_env_wins_over_everything`
- `derive_project_name_dotenv_wins_over_compose_and_fallback`
- `derive_project_name_compose_name_wins_over_fallback`
- `derive_project_name_skips_compose_name_when_not_explicitly_declared`
-
`derive_project_name_omits_suffix_when_compose_file_outside_devcontainer_dir`
- `derive_project_name_normalizes_compose_path_for_rule_4`
- `compose_fragment_declares_name_detects_top_level_name_key` (covers
block, quoted-key, and flow-style roots, plus parse failure →
not-declared)
- `is_missing_file_error_only_accepts_notfound_and_isadirectory`
- [x] `cargo fmt --all` — clean
- [x] `./script/clippy -p dev_container` — clean
- [x] **End-to-end with fixture**
[antont/zed-devcontainer-compose-test](https://github.com/antont/zed-devcontainer-compose-test):
- Build `zed` from this branch.
- Clean slate: `docker ps -a --filter
"label=devcontainer.local_folder=$PWD" -q | xargs -r docker rm -f`
- `zed --dev-container /path/to/devcontainer-compose-test` → Zed creates
container under project `devcontainer-compose-test_devcontainer` (was
`compose_duplicate_repro` before the fix).
- `devcontainer up --workspace-folder $PWD` → CLI reports the same
`containerId` Zed created; no second compose project is introduced.
- Captured: `devcontainer-compose-test_devcontainer-app-1`,
`composeProjectName: "devcontainer-compose-test_devcontainer"` reported
by both tools.
Release Notes:
- Fixed dev container Docker Compose project name now matches the full
`getProjectName` precedence from the reference devcontainer CLI
(`COMPOSE_PROJECT_NAME` in the environment, then in the workspace
`.env`, then an explicit top-level `name:` on the merged compose config,
then the basename of the first compose file's directory — with the
`_devcontainer` suffix only when that directory is
`<workspace>/.devcontainer`). This prevents duplicate containers when
the same folder is opened with both Zed and the devcontainer CLI / VS
Code.
---------
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
Self-Review Checklist:
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable
Closes#52928
Release Notes:
- Fixed handling of multi-stage and stage-specified dockerfiles in dev
container manifests
- Fixed the way we find the base image in a dev container when build
args need expansion
## Context
Closes#11473
In-house Zed implementation of devcontainers. Replaces the dependency on
the [reference implementation](https://github.com/devcontainers/cli) via
Node.
This enables additional features with this implementation:
1. Zed extensions can be specified in the `customizations` block, via
this syntax in `devcontainer.json:
```
...
"customizations": {
"zed": {
"extensions": ["vue", "ruby"],
},
},
```
2.
[forwardPorts](https://containers.dev/implementors/json_reference/#general-properties)
are supported for multiple ports proxied to the host
## How to Review
<!-- Help reviewers focus their attention:
- For small PRs: note what to focus on (e.g., "error handling in
foo.rs")
- For large PRs (>400 LOC): provide a guided tour — numbered list of
files/commits to read in order. (The `large-pr` label is applied
automatically.)
- See the review process guidelines for comment conventions -->
## Self-Review Checklist
<!-- Check before requesting review: -->
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable
Release Notes:
- Improved devcontainer implementation by moving initialization and
creation in-house
This will help with test times (in some cases), as nextest cannot figure
out whether a given rdep is actually an alive edge of the build graph
Closes #ISSUE
Before you mark this PR as ready for review, make sure that you have:
- [ ] Added a solid test coverage and/or screenshots from doing manual
testing
- [ ] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
Release Notes:
- N/A
Release Notes:
- Added agent panel restoration. Now restarting your editor won't cause
your thread to be forgotten.
---------
Co-authored-by: Anthony Eid <56899983+Anthony-Eid@users.noreply.github.com>
Co-authored-by: Eric Holk <eric@zed.dev>
Co-authored-by: Danilo Leal <67129314+danilo-leal@users.noreply.github.com>
Co-authored-by: Anthony Eid <anthony@zed.dev>
Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>
Co-authored-by: Cameron Mcloughlin <cameron.studdstreet@gmail.com>
Closes#48683
Per the devcontainer spec, `.devcontainer.json` in the project root is
a valid config location. It is only used when no configurations are
found inside `.devcontainer/`.
Extract `find_configs_in_snapshot` for testability and add tests.
Release Notes:
- Added support for `.devcontainer.json` in project root
It's happeningggggg
Release Notes:
- Changed the Agent Panel so that the Active Thread is restored on
restart.
---------
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Danilo Leal <daniloleal09@gmail.com>
Co-authored-by: Anthony Eid <anthony@zed.dev>
Co-authored-by: Danilo Leal <67129314+danilo-leal@users.noreply.github.com>
Co-authored-by: Richard Feldman <richard@zed.dev>
Co-authored-by: Zed Zippy <234243425+zed-zippy[bot]@users.noreply.github.com>
Adds the ability to create a dev container definition from scratch.
Additionally, separates devcontainer logic out into its own crate, since
it was getting sufficiently complex to separate from the
`recent_projects` crate.
A screen recording of the modal experience:
https://github.com/user-attachments/assets/f6cf95e1-eb7b-4ca3-86c7-c1cbc26ca557
Release Notes:
- Added modal to initialize a dev container definition in the project
with `projects: initialize dev container`
- Added podman support for dev container actions with the `use_podman`
setting
- Improved devcontainer error handling
---------
Co-authored-by: Sam Coward <idoru42@gmail.com>
