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Cameron Mcloughlin 63f725e8d6
markdown: Merman (#57644)
Big PR that replaces `mermaid-rs` with `merman`.

Adds a new crate `mermaid_render` that exposes a simple API for
rendering a mermaid diagram to an SVG string.

## Why is it so big?

Some of this is explained in the crate-level docs for `mermaid_render`,
but the short version is:
- `mermaid-rs` emits "good enough" SVGs for most use cases. It also
ships with a reasonable default theme
- `merman` emits *very accurate* SVGs, but with borderline unusable CSS
- Most of the new code in this PR are a series of passes to clean up the
output SVG by:
  - Injecting good CSS
  - Fixing issues in the `merman`-generated SVGs
- Tweaking the final result to avoid issues with `usvg` and `resvg`,
which are what will eventually be used to rasterize the SVG
- This code *could* be much smaller, but the following design decisions
made it take a lot more code:
  - Using a real XML parser instead of basic string manipulation
  - Avoiding allocating strings in as many places as possible

Because of this, the design is as follows:
- First, construct a `merman` theme from the user's theme, and render
the mermaid to an SVG string
- Post-process - each step is roughly a `fn(Iterator<Item =
Event<'short>>) -> Iterator<Item = Event<'short>>`, where `Event` is the
type for events produced by `quick-xml` (a pull-based XML parser)
 

## Note for reviewers

It's a big diff, sorry 😅 happy to pair review. 

The new crate is essentially a leaf crate - it does technically depend
on `gpui`, but only for the `Hsla` and `Rgba` types. Extracting a new
`gpui_color` crate felt like overkill for this already-very-big PR.

Each post-process pass is in its own submodule, and has a doc comment
explaining the before/after. Note that bugs in this code are perhaps
less serious than bugs in other parts of the code:
- The code has been thoroughly audited for potentially-panicking code
paths - as far as I know, there are none (excluding some `.expect()`s on
calls to `write!` with `String`, which is [cannot return `Err`][string
write])
- A bug in this code (given that it will not cause a panic) will, at
worst, result in an invalid diagram being rendered, or simply falling
back to showing the code.
- The current `mermaid-rs` renderer *already* does this in quite a lot
of cases, sometimes showing outright misleading information.
---

Some eye candy:
| Before (`mermaid-rs`) | After (`merman`) |
| - | - |
| <img width="1227" height="340" alt="image"
src="https://github.com/user-attachments/assets/58d6904e-64bc-478a-8d67-f75ad4ccbc9e"
/> | <img width="1169" height="482" alt="image"
src="https://github.com/user-attachments/assets/d4bb9cd5-240f-4bf6-ba7f-4862049ed8b0"
/> |
| <img width="842" height="564" alt="image"
src="https://github.com/user-attachments/assets/1668a50d-68f6-4145-8cef-359e4c6a4589"
/> | <img width="869" height="543" alt="image"
src="https://github.com/user-attachments/assets/2ec1a7eb-fc3c-4392-b577-1ad52396b87c"
/> |
| Failed to render | <img width="822" height="1123" alt="image"
src="https://github.com/user-attachments/assets/a97308a1-6b3a-48b6-9778-abf3507c6ad3"
/> |
| <img width="252" height="517" alt="image"
src="https://github.com/user-attachments/assets/dbf86274-004a-4ee4-be89-cc6ff4f6cf35"
/> | <img width="361" height="680" alt="image"
src="https://github.com/user-attachments/assets/8457b6ed-3ca9-4bed-9496-60388ba08206"
/> |
| <img width="550" height="1050" alt="image"
src="https://github.com/user-attachments/assets/c21b8513-fb86-422e-870a-015e0add783a"
/> | <img width="819" height="1148" alt="image"
src="https://github.com/user-attachments/assets/ca646165-302d-41aa-8da5-39e89c96ebb7"
/> |
| <img width="1218" height="225" alt="image"
src="https://github.com/user-attachments/assets/3006a1bf-efe6-46f5-9f9d-289a3fdf9adc"
/> | <img width="1118" height="965" alt="image"
src="https://github.com/user-attachments/assets/90d76098-bf3d-4c69-bc9b-00dd9cbf6990"
/> |
| <img width="800" height="584" alt="image"
src="https://github.com/user-attachments/assets/f688693b-df3d-4514-b105-ccaa3874e40c"
/> | <img width="1153" height="417" alt="image"
src="https://github.com/user-attachments/assets/eeb05f58-7184-4321-a47b-ea3cc53f0d02"
/> |
| <img width="539" height="464" alt="image"
src="https://github.com/user-attachments/assets/0076105d-eef9-4011-9b9a-581918575e49"
/> | <img width="638" height="556" alt="image"
src="https://github.com/user-attachments/assets/72a51966-c296-48d0-b1e2-66835b1a0d5b"
/> |
| <img width="607" height="430" alt="image"
src="https://github.com/user-attachments/assets/d3530814-532b-41ed-a2b6-fd5740d8db58"
/> | <img width="725" height="489" alt="image"
src="https://github.com/user-attachments/assets/c43687d9-f426-4cb8-8a45-23a3c0070c8f"
/> |
| <img width="869" height="577" alt="image"
src="https://github.com/user-attachments/assets/b607f3fd-136c-4f41-a88e-596520e276b9"
/> | <img width="784" height="586" alt="image"
src="https://github.com/user-attachments/assets/22305a64-b4d0-474a-b6f6-8973f2bca933"
/> |
| <img width="1214" height="263" alt="image"
src="https://github.com/user-attachments/assets/183ff0df-a6f3-470c-b271-8099c3e33044"
/> | <img width="1195" height="632" alt="image"
src="https://github.com/user-attachments/assets/868bcb7f-62c6-4d20-ba1e-3f25f8165fff"
/> |
| <img width="573" height="597" alt="image"
src="https://github.com/user-attachments/assets/6414e409-b879-4892-8ef6-89489219b56f"
/> | <img width="578" height="608" alt="image"
src="https://github.com/user-attachments/assets/8ac71b03-f603-4e32-87aa-b993317d4e29"
/> |
| <img width="543" height="472" alt="image"
src="https://github.com/user-attachments/assets/1f19929c-cf07-4287-b9cf-b976eea9faaa"
/> | <img width="760" height="599" alt="image"
src="https://github.com/user-attachments/assets/73926075-db47-4eb1-854e-7aee30522684"
/> |
| <img width="1205" height="219" alt="image"
src="https://github.com/user-attachments/assets/5f3dc936-4b89-44f4-a00a-4dbc47e06504"
/> | <img width="1133" height="349" alt="image"
src="https://github.com/user-attachments/assets/e62901ff-9d75-4fde-a30e-974ff2e783b1"
/> |


Release Notes:

- Improved: Mermaid diagrams now render faster and more accurately

[string write]:
https://doc.rust-lang.org/src/alloc/string.rs.html#3342-3354

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>
Co-authored-by: zed-zippy[bot] <234243425+zed-zippy[bot]@users.noreply.github.com>
2026-05-27 16:27:18 +00:00
.cargo livekit: Use our build of libwebrtc.a (#51433) 2026-03-16 10:47:36 +01:00
.cloudflare Staged docs releases (#50136) 2026-04-30 11:10:14 +00:00
.config Increase timeout for test_random_blocks (#50724) 2026-03-04 12:25:12 -05:00
.factory Add humanizer skill for AI writing pattern detection (#50021) 2026-02-24 14:58:52 -06:00
.github Duplicate Bot: Add more context for triagers (V3) (#57647) 2026-05-25 14:29:13 +00:00
.zed agent: Remove old edit file tool (#55612) 2026-05-04 09:54:39 +00:00
assets Rename agent threads from the sidebar (#57656) 2026-05-26 17:55:09 +00:00
ci Move Nightly release to gh-workflow (#41349) 2025-10-28 13:57:23 -06:00
crates markdown: Merman (#57644) 2026-05-27 16:27:18 +00:00
docs docs: Update information regarding rules/skills (#57824) 2026-05-27 13:30:08 +00:00
extensions docs: Fix typo in EXTRACTION.md (#55106) 2026-04-28 19:18:44 +00:00
legal Update legal docs to reflect new terms of service (#50530) 2026-03-02 12:36:31 -08:00
nix nix: Fix build on x86_64-linux (#52917) 2026-04-01 20:50:04 +02:00
script Duplicate Bot: Handle failure modes better (#57663) 2026-05-25 16:49:51 +00:00
tooling extension_ci: Bump extension CLI version to 2a00db0 (#57098) 2026-05-19 07:01:38 +00:00
.git-blame-ignore-revs Add PR 50413 to .git-blame-ignore-revs (#50421) 2026-03-01 00:50:33 +01:00
.gitattributes windows: Make sure zed.sh using the correct line ending (#37650) 2025-09-05 16:25:55 +00:00
.gitignore build: Allow pinning of webrtc build artifacts (✈️ edition) (#55336) 2026-05-04 06:22:51 +00:00
.mailmap Update .mailmap (#47413) 2026-01-22 23:57:26 +05:30
.prettierrc ci: Add check for formatting default.json (#30034) 2025-05-06 18:55:26 +00:00
.rules Update AI rules to reflect that AsyncApp updates are now infallible (#54818) 2026-04-24 19:04:32 +00:00
AGENTS.md ai: Symlink an AGENTS.md file to .rules (#45939) 2026-01-19 15:29:42 +01:00
Cargo.lock markdown: Merman (#57644) 2026-05-27 16:27:18 +00:00
Cargo.toml markdown: Merman (#57644) 2026-05-27 16:27:18 +00:00
CLAUDE.md Initial .rules file for agent with symlinks for other rules file paths (#29014) 2025-04-17 23:41:23 +00:00
clippy.toml Revert "Revert scheduler update (#46659)" (#46671) 2026-01-14 07:19:13 +00:00
CODE_OF_CONDUCT.md Remove community content from docs and point to zed.dev (#19895) 2024-10-29 09:44:58 -04:00
compose.yml Remove Postgres and stripe-mock from Docker Compose (#48313) 2026-02-04 03:42:58 +00:00
CONTRIBUTING.md Add Zed Feature Process document (#50747) 2026-03-06 14:14:53 -08:00
debug.plist
default.nix nix: Use flake-parts, partitions, and treefmt-nix (#45321) 2026-02-02 14:26:42 +00:00
Dockerfile-collab Bump Rust version to 1.94 (#51086) 2026-03-30 09:06:59 +00:00
Dockerfile-collab.dockerignore ci: Move collab to Dockerfile-collab (#18515) 2024-09-30 16:14:26 -04:00
Dockerfile-cross.dockerignore Add remote server cross compilation (#19136) 2024-10-12 23:23:56 -07:00
Dockerfile-distros Removal of mold/wild scripts and mentions in docs (#53078) 2026-04-08 21:20:02 +03:00
Dockerfile-distros.dockerignore Support More Linux (#18480) 2024-09-30 17:46:21 -04:00
flake.lock Rust 1.95 (#55104) 2026-04-29 10:27:47 +00:00
flake.nix Try to improve nix caching (#48297) 2026-02-03 20:31:02 -07:00
GEMINI.md Add missing GEMINI.md rule file for gemini-cli (#38885) 2025-10-02 09:47:29 -04:00
LICENSE-AGPL Update license year (#24191) 2025-02-04 09:02:59 -05:00
LICENSE-APACHE Update license year (#24191) 2025-02-04 09:02:59 -05:00
LICENSE-GPL
livekit.yaml Add LiveKit server to Docker Compose (#7907) 2024-02-16 10:49:48 -05:00
lychee.toml ci: Check for broken links (#30844) 2025-06-06 09:39:35 +00:00
Procfile Update instructions for local collaboration (#35689) 2025-08-06 11:10:28 -07:00
Procfile.all Add agent thread sharing (#46140) 2026-01-06 12:49:51 -08:00
Procfile.web Remove PostgREST (#41299) 2025-10-27 13:27:59 -04:00
README.md Add sponsor button to main Zed repo (#46807) 2026-01-14 10:38:51 -06:00
renovate.json Remove workspace-hack (#40216) 2025-10-17 18:58:14 +00:00
REVIEWERS.conl Remove past reviewer (#51767) 2026-03-17 16:34:35 +00:00
rust-toolchain.toml Rust 1.95 (#55104) 2026-04-29 10:27:47 +00:00
rustfmt.toml nix: Use flake-parts, partitions, and treefmt-nix (#45321) 2026-02-02 14:26:42 +00:00
shell.nix nix: Use flake-parts, partitions, and treefmt-nix (#45321) 2026-02-02 14:26:42 +00:00
typos.toml markdown: Merman (#57644) 2026-05-27 16:27:18 +00:00

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