docs: add an application observability page

[ogabrielluiz]

Adds a docs page for the application observability surface introduced in #14213, so it should land after that one.

The code shipped with good docstrings, but operators do not read docstrings. The new page covers:

• The two-variable quickstart, and the lfx[otel] extra for standalone lfx.
• What each signal actually measures: RED per endpoint, process-level runtime health, queue depth, the flow.execute span, and trace_id correlation.
• The full OTEL_* configuration table, plus the local Prometheus option and why metrics are pushed rather than only scraped.
• The stable HTTP semantic conventions rename, with a before/after table and the http/dup value for emitting both while migrating. Anyone with dashboards on http.server.duration needs this.

It also states the boundary plainly, including the parts that are easy to get wrong:

• Prompts, completions, gen_ai token metrics and outbound LLM call spans do not reach the operator's backend.
• The log channel is filtered by severity, not content, so an ERROR record can still carry flow-derived text.
• session_id is exported exactly as the caller supplies it, so deployments using emails or usernames as session IDs will send those.

Placed at the top level of the Observability sidebar next to Logs and Traces, rather than under Monitoring, since that subcategory is the LLM tracing vendors and this is the operator lens. The page says so up front and links across, so the two do not get conflated.

No code changes.

Summary by CodeRabbit

• Documentation
  • Added guidance for monitoring Langflow application health and flow execution through OTLP observability.
  • Documented setup prerequisites, environment variables, supported signals, exported data, and privacy considerations.
  • Clarified that OTLP export is disabled unless an endpoint is configured.
  • Added the OTLP observability guide to the documentation navigation.

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Walkthrough

Changes

OTLP observability documentation

Layer / File(s)	Summary
OTLP overview and setup docs/docs/Develop/observability-otlp.mdx	Introduces application observability via OTLP, prerequisites, and the quickstart configuration and verification workflow.
Signals, configuration, and export boundaries docs/docs/Develop/observability-otlp.mdx	Documents measurable signals, environment variables, OTLP metric delivery, exported data boundaries, filtering, and correlation warnings.
Metric migration and documentation navigation docs/docs/Develop/observability-otlp.mdx, docs/sidebars.js	Describes HTTP semantic-convention migration and adds the new observability page to the documentation sidebar.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: mendonk

🚥 Pre-merge checks | ✅ 9

✅ Passed checks (9 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding an application observability documentation page.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Test Coverage For New Implementations	✅ Passed	Docs-only PR: changed files are a new .mdx page and sidebar entry, with no code paths or test files added.
Test Quality And Coverage	✅ Passed	Docs-only PR: only two documentation files changed, with no implementation or test code to evaluate for coverage.
Test File Naming And Structure	✅ Passed	Changed test files use conventional names and structure (test_*.py, *.test.tsx, *.spec.ts) with descriptive pytest/Playwright cases; no naming issues found.
Excessive Mock Usage Warning	✅ Passed	PR changes only docs/sidebar; no test files were modified, so mock usage is not applicable.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs-application-observability

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[github-actions]

✅ Test Coverage Advisor

No source changes detected without accompanying tests. Thanks for keeping coverage up! 🎉

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docs/docs/Develop/observability-otlp.mdx`:
- Line 4: Remove the unsupported description frontmatter field from the
observability OTLP documentation page, leaving only the existing title and slug
fields in its frontmatter.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📥 Commits

Reviewing files that changed from the base of the PR and between 2b20764 and 2a400d5.

📒 Files selected for processing (2)

• docs/docs/Develop/observability-otlp.mdx
• docs/sidebars.js

[coderabbitai]

📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Remove the unsupported frontmatter field.

Line 4 violates the page-frontmatter convention; retain only title and slug.

As per coding guidelines, “Use only title and slug in frontmatter for Docusaurus pages; do not include description or sidebar_position.”

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@docs/docs/Develop/observability-otlp.mdx` at line 4, Remove the unsupported
description frontmatter field from the observability OTLP documentation page,
leaving only the existing title and slug fields in its frontmatter.

Source: Coding guidelines

[github-actions]

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