chore(event formatter): add event formatter to sentry backend by shayna-ch · Pull Request #119250 · getsentry/sentry

shayna-ch · 2026-07-08T19:15:33Z

Adds event formatter module to sentry backend.
how it works: serialized event → adapter → model → formatter → text

adapter.py

this takes a serialized event from sentry and turns it into an event object (and its components like breadcrumbs).

formatter.py

this takes the event object from the adapter and turns it into text (markdown or xml)

limits.py

holds char/count limits for stacktraces, breadcrumbs, etc...
based of seers limits

models.py

has the object definitions for event and event components
based off seer's event details model

sections.py

defines what each block of text contains, plus the section order and the format_issue entry point

Example Formatted Outputs

Markdown:

## Title
ValueError: invalid literal for int()

## Exception
ValueError: invalid literal for int() with base 10: 'abc'
**Handled:** No
parse in app/utils.py [Line 12] (In app)
    return int(value)  <-- SUSPECT LINE
vars: value="'abc'"
------
handle_request in app/views.py [Line 88] (In app)
    qty = request.GET['qty']
    return int(qty)  <-- SUSPECT LINE

## Breadcrumbs
[info] auth: user logged in
[warning] cart: qty parsed from query string

## Request
GET https://shop.example.com/api/checkout
{'qty': 'abc'}

## Tags
**environment:** production
**transaction:** /api/checkout

## User
**ID:** 42
**Email:** jane@example.com
**IP:** 203.0.113.5

XML:

<title>
ValueError: invalid literal for int()
</title>

<exception>
ValueError: invalid literal for int() with base 10: 'abc'
<handled>No</handled>
<code lang="">parse in app/utils.py [Line 12] (In app)
    return int(value)  <-- SUSPECT LINE
vars: value="'abc'"
------
handle_request in app/views.py [Line 88] (In app)
    qty = request.GET['qty']
    return int(qty)  <-- SUSPECT LINE</code>
</exception>

<breadcrumbs>
[info] auth: user logged in
[warning] cart: qty parsed from query string
</breadcrumbs>

<request>
GET https://shop.example.com/api/checkout
<code>{'qty': 'abc'}</code>
</request>

<tags>
<environment>production</environment>
<transaction>/api/checkout</transaction>
</tags>

<user>
<id>42</id>
<email>jane@example.com</email>
<ip>203.0.113.5</ip>
</user>

resolves ID-1699

shayna-ch · 2026-07-09T21:19:12Z

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shayna-ch · 2026-07-09T21:47:53Z

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shayna-ch · 2026-07-09T22:35:55Z

bugbot run

shayna-ch · 2026-07-13T16:48:30Z

bugbot run

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linear-code · 2026-07-13T17:45:48Z

ID-1699

cvxluo · 2026-07-13T18:04:30Z

+    )
+
+
+def _breadcrumb(v: Mapping[str, Any]) -> Breadcrumb:


do we really need so many helpers? a lot of these helpers seem to be parsing unknown Anys, which is helpful, but all the types are fully optional anyways, so it doesn't provide much information.

true, removed the ones that didn't have extra logic and moved to aliases

cvxluo · 2026-07-13T18:05:01Z

 )

+# Enables the shared issue/event formatter module (markdown/xml output for LLMs).
+register(


what is this option for?

just so i can test locally while I implement the surfaces. eventually I will prob move it to a feature flag

cvxluo · 2026-07-13T18:06:45Z

+]
+
+
+def format_issue(


i'm having trouble reviewing this since it's hard to tell how this is going to be used (e.g. are we really taking in a fully unknown Mapping[str, Any] every time we use this?). do you have an example of where we'd be calling format_issue?

sentry · 2026-07-13T19:58:22Z

+    def field(self, key: str, value: str) -> str:
+        tag = slug(key)
+        return f"<{tag}>{value}</{tag}>"
+
+    def code_block(self, text: str) -> str:
+        return f"<code>{text}</code>"


Bug: The XmlFormatter does not escape special characters like < and > in event data, producing invalid XML for stack traces with generics.
_{Severity: HIGH}

Suggested Fix

Apply an XML escaping function, such as xml.sax.saxutils.escape, to all dynamic content before it is embedded within XML tags in the XmlFormatter's field(), code_block(), and block() methods.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not valid. Location: src/sentry/issues/formatting/formatter.py#L67-L72 Potential issue: The `XmlFormatter` class does not escape special XML characters like `<`, `>`, and `&`. When formatting event data that contains these characters, such as stack traces from languages like Java or C++ that use generic types (e.g., `Map<String, List<Integer>>`), the formatter produces syntactically invalid XML. This will cause parsing errors for downstream consumers that expect valid XML, such as the intended LLM integration. The issue affects the `field()`, `code_block()`, and `block()` methods.

sentry · 2026-07-13T21:09:02Z

+    package: str | None = None
+    line_no: int | None = Field(None, alias="lineNo")
+    col_no: int | None = Field(None, alias="colNo")
+    context: list[tuple[int, str | None]] = []  # [(line_no, source_line), ...]


Bug: The Frame.context field is not optional, but serialized events can contain "context": null. This will cause a ValidationError and crash the issue formatting process.
_{Severity: HIGH}

Suggested Fix

Modify the Frame.context field definition to allow None. Change context: list[tuple[int, str | None]] = [] to context: list[tuple[int, str | None]] | None = None. This will make Pydantic correctly handle null values for this field during deserialization.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not valid. Location: src/sentry/issues/formatting/models.py#L27 Potential issue: The `Frame.context` field in `src/sentry/issues/formatting/models.py` is defined as a non-optional list. However, Sentry events can contain frames where the `context` is `null`, especially for code without available source context (e.g., minified JavaScript or native code). When `format_issue()` attempts to parse such an event, Pydantic will raise a `ValidationError` because `null` is not a valid list. Since there is no error handling around the model parsing in `event_response_to_model()`, this exception will propagate uncaught, causing the entire issue formatting pipeline to crash for that event.

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 3 total unresolved issues (including 2 from previous reviews).

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github-actions Bot added the Scope: Backend Automatically applied to PRs that change backend components label Jul 8, 2026

shayna-ch added 7 commits July 8, 2026 12:25

models

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formatter

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adapter

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limits

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shayna-ch changed the title ~~formatter~~ chore(event formatter): add event formatter to sentry backend Jul 9, 2026

shayna-ch added 2 commits July 9, 2026 13:46

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shayna-ch marked this pull request as ready for review July 13, 2026 17:30

shayna-ch requested review from a team as code owners July 13, 2026 17:30

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shayna-ch commented Jul 8, 2026 •

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