Revert "editor: Add language detection for untitled buffers (#61201)" - #61351
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ChristopherBiscardi merged 1 commit intoJul 20, 2026
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…stries#61201)" This reverts commit 690c7fa.
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showing the issue: Screen.Recording.2026-07-20.at.9.27.28.AM.mov |
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ChristopherBiscardi
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Sorry for introducing this issue, and thank you for pointing it out. I’ll look into a fix, potentially using VS Code’s implementation as a reference. |
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No stress, I should've caught it in testing before merge but I did not exercise this specific pattern in a markdown file. It seems to be that the betlang detection thinks a markdown document with a lot of list elements is yaml. Adding a codeblock or similar "fixes" it. For example, where this is always markdown: # markdown
```rust
this is markdown, always
```
- this
- andthis is yaml |
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…stries#61201)" (zed-industries#61351) This reverts commit 55b1b59. # Objective language detection is firing very often in channel notes, often picking YAML instead of markdown, causing some language-detection flickering. cc/ @amtoaer (author of the original PR)
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…1412) # Objective Closes zed-industries#4868. Reintroduce automatic language detection for user-created untitled buffers without allowing it to override language choices made by users or owning surfaces. More details: + zed-industries#61201 + zed-industries#61351 ## Solution VS Code distinguishes between inferred and explicitly selected languages, and only continues automatic detection in the former state. This change introduces a buffer-local opt-in flag with the same purpose. It defaults to disabled and is enabled only for user-created untitled buffers and restored untitled buffers that did not persist a language. Choosing a language through the language picker disables detection, while automatically detected languages remain eligible for later redetection. Buffers whose language is assigned by their owning surface, such as Channel Notes, never opt in. Rather than adding persisted state or changing the database schema, restoration reuses the existing optional serialized language. An opted-in buffer that remains Plain Text is serialized without a language and resumes detection after restoration. Once automatic detection has selected a language, that language is serialized normally and restoration leaves detection disabled, effectively treating it as an explicit selection. This also matches VS Code's effective default after restoration. Candidate selection adopts VS Code's confidence-group filtering. Results below the minimum confidence are discarded, and candidate groups are accepted only after a clear confidence gap. The detector then selects the first available Zed language without eagerly loading every candidate. I then added a separate switching rule: Zed keeps the current language unless another candidate has a clear confidence advantage, reducing language changes as model scores fluctuate during editing. Model inference runs off-thread on a bounded sample, and stale results are discarded. I also evaluated penalizing YAML and using stricter global switching thresholds, but neither reliably resolves the ambiguity between Markdown and YAML. In the reproduction from zed-industries#61351, Betlang assigns YAML more than 80% confidence during editing and peaks around 90%. This is reasonable from the content alone: `#` denotes a YAML comment, while `-` denotes a sequence item. Adding ordinary prose or a fenced code block shifts the model strongly toward Markdown. A fixed penalty would overfit this example and risk suppressing legitimate YAML detection. Since known-language buffers do not opt in and manual language selection takes precedence, I consider this level of ambiguity acceptable and prefer not to introduce language-specific score tuning. Model inference itself is fast. As noted in zed-industries#61201: > In release builds on Linux with an Intel Core i5-13600KF, the `betlang::detect` call alone typically completes within 3 ms when processing the maximum sampled input. The main concern is the work surrounding inference. Without debouncing, rapid typing creates a snapshot and launches a background detection task on every keystroke, while the detected language may change before the user has finished typing. This change therefore adds a 200 ms debounce delay, allowing detection to run and update the language only after the user pauses. ## Testing Automated coverage verifies that short inputs remain Plain Text, sufficient Rust content is detected as Rust, replacing it with Go content triggers redetection, and manually selecting Plain Text prevents subsequent automatic changes. Restoration coverage verifies that a stored language keeps detection disabled, while an empty language-less untitled buffer resumes detection. Beyond the automated tests, I manually tested automatic language detection while editing untitled buffers. ## 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 adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable ## Showcase https://github.com/user-attachments/assets/103fc731-e12e-48d6-ae89-03978f1c9d74 --- Release Notes: - Added automatic language detection for untitled buffers. --------- Co-authored-by: Max Stevens <maxstevens2708@gmail.com> Co-authored-by: Christopher Biscardi <chris@christopherbiscardi.com>
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…1412) # Objective Closes zed-industries#4868. Reintroduce automatic language detection for user-created untitled buffers without allowing it to override language choices made by users or owning surfaces. More details: + zed-industries#61201 + zed-industries#61351 ## Solution VS Code distinguishes between inferred and explicitly selected languages, and only continues automatic detection in the former state. This change introduces a buffer-local opt-in flag with the same purpose. It defaults to disabled and is enabled only for user-created untitled buffers and restored untitled buffers that did not persist a language. Choosing a language through the language picker disables detection, while automatically detected languages remain eligible for later redetection. Buffers whose language is assigned by their owning surface, such as Channel Notes, never opt in. Rather than adding persisted state or changing the database schema, restoration reuses the existing optional serialized language. An opted-in buffer that remains Plain Text is serialized without a language and resumes detection after restoration. Once automatic detection has selected a language, that language is serialized normally and restoration leaves detection disabled, effectively treating it as an explicit selection. This also matches VS Code's effective default after restoration. Candidate selection adopts VS Code's confidence-group filtering. Results below the minimum confidence are discarded, and candidate groups are accepted only after a clear confidence gap. The detector then selects the first available Zed language without eagerly loading every candidate. I then added a separate switching rule: Zed keeps the current language unless another candidate has a clear confidence advantage, reducing language changes as model scores fluctuate during editing. Model inference runs off-thread on a bounded sample, and stale results are discarded. I also evaluated penalizing YAML and using stricter global switching thresholds, but neither reliably resolves the ambiguity between Markdown and YAML. In the reproduction from zed-industries#61351, Betlang assigns YAML more than 80% confidence during editing and peaks around 90%. This is reasonable from the content alone: `#` denotes a YAML comment, while `-` denotes a sequence item. Adding ordinary prose or a fenced code block shifts the model strongly toward Markdown. A fixed penalty would overfit this example and risk suppressing legitimate YAML detection. Since known-language buffers do not opt in and manual language selection takes precedence, I consider this level of ambiguity acceptable and prefer not to introduce language-specific score tuning. Model inference itself is fast. As noted in zed-industries#61201: > In release builds on Linux with an Intel Core i5-13600KF, the `betlang::detect` call alone typically completes within 3 ms when processing the maximum sampled input. The main concern is the work surrounding inference. Without debouncing, rapid typing creates a snapshot and launches a background detection task on every keystroke, while the detected language may change before the user has finished typing. This change therefore adds a 200 ms debounce delay, allowing detection to run and update the language only after the user pauses. ## Testing Automated coverage verifies that short inputs remain Plain Text, sufficient Rust content is detected as Rust, replacing it with Go content triggers redetection, and manually selecting Plain Text prevents subsequent automatic changes. Restoration coverage verifies that a stored language keeps detection disabled, while an empty language-less untitled buffer resumes detection. Beyond the automated tests, I manually tested automatic language detection while editing untitled buffers. ## 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 adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable ## Showcase https://github.com/user-attachments/assets/103fc731-e12e-48d6-ae89-03978f1c9d74 --- Release Notes: - Added automatic language detection for untitled buffers. --------- Co-authored-by: Max Stevens <maxstevens2708@gmail.com> Co-authored-by: Christopher Biscardi <chris@christopherbiscardi.com>
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…stries#61201)" (zed-industries#61351) This reverts commit 690c7fa. # Objective language detection is firing very often in channel notes, often picking YAML instead of markdown, causing some language-detection flickering. cc/ @amtoaer (author of the original PR)
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…1412) # Objective Closes zed-industries#4868. Reintroduce automatic language detection for user-created untitled buffers without allowing it to override language choices made by users or owning surfaces. More details: + zed-industries#61201 + zed-industries#61351 ## Solution VS Code distinguishes between inferred and explicitly selected languages, and only continues automatic detection in the former state. This change introduces a buffer-local opt-in flag with the same purpose. It defaults to disabled and is enabled only for user-created untitled buffers and restored untitled buffers that did not persist a language. Choosing a language through the language picker disables detection, while automatically detected languages remain eligible for later redetection. Buffers whose language is assigned by their owning surface, such as Channel Notes, never opt in. Rather than adding persisted state or changing the database schema, restoration reuses the existing optional serialized language. An opted-in buffer that remains Plain Text is serialized without a language and resumes detection after restoration. Once automatic detection has selected a language, that language is serialized normally and restoration leaves detection disabled, effectively treating it as an explicit selection. This also matches VS Code's effective default after restoration. Candidate selection adopts VS Code's confidence-group filtering. Results below the minimum confidence are discarded, and candidate groups are accepted only after a clear confidence gap. The detector then selects the first available Zed language without eagerly loading every candidate. I then added a separate switching rule: Zed keeps the current language unless another candidate has a clear confidence advantage, reducing language changes as model scores fluctuate during editing. Model inference runs off-thread on a bounded sample, and stale results are discarded. I also evaluated penalizing YAML and using stricter global switching thresholds, but neither reliably resolves the ambiguity between Markdown and YAML. In the reproduction from zed-industries#61351, Betlang assigns YAML more than 80% confidence during editing and peaks around 90%. This is reasonable from the content alone: `#` denotes a YAML comment, while `-` denotes a sequence item. Adding ordinary prose or a fenced code block shifts the model strongly toward Markdown. A fixed penalty would overfit this example and risk suppressing legitimate YAML detection. Since known-language buffers do not opt in and manual language selection takes precedence, I consider this level of ambiguity acceptable and prefer not to introduce language-specific score tuning. Model inference itself is fast. As noted in zed-industries#61201: > In release builds on Linux with an Intel Core i5-13600KF, the `betlang::detect` call alone typically completes within 3 ms when processing the maximum sampled input. The main concern is the work surrounding inference. Without debouncing, rapid typing creates a snapshot and launches a background detection task on every keystroke, while the detected language may change before the user has finished typing. This change therefore adds a 200 ms debounce delay, allowing detection to run and update the language only after the user pauses. ## Testing Automated coverage verifies that short inputs remain Plain Text, sufficient Rust content is detected as Rust, replacing it with Go content triggers redetection, and manually selecting Plain Text prevents subsequent automatic changes. Restoration coverage verifies that a stored language keeps detection disabled, while an empty language-less untitled buffer resumes detection. Beyond the automated tests, I manually tested automatic language detection while editing untitled buffers. ## 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 adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable ## Showcase https://github.com/user-attachments/assets/103fc731-e12e-48d6-ae89-03978f1c9d74 --- Release Notes: - Added automatic language detection for untitled buffers. --------- Co-authored-by: Max Stevens <maxstevens2708@gmail.com> Co-authored-by: Christopher Biscardi <chris@christopherbiscardi.com>
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This reverts commit 690c7fa.
Objective
language detection is firing very often in channel notes, often picking YAML instead of markdown, causing some language-detection flickering.
cc/ @amtoaer (author of the original PR)