Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add PostHog/posthog-foss --skill diagnosing-stacktrace-symbolicationgit clone --depth 1 https://github.com/PostHog/posthog-fossWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/posthog/posthog-foss/diagnosing-stacktrace-symbolication)<a href="https://agentmods.dev/skills/posthog/posthog-foss/diagnosing-stacktrace-symbolication"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/diagnosing-stacktrace-symbolication/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/posthog/posthog-foss/diagnosing-stacktrace-symbolication"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/diagnosing-stacktrace-symbolication.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium MCP Rug Pull · line 91 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00165 | $0.01821 |
| Opus 5 | $0.00082 | $0.00911 |
| Sonnet 5 | $0.00033 | $0.00364 |
| Haiku 4.5 | $0.00016 | $0.00182 |
Grade A, and why
diagnosing-stacktrace-symbolication scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- diagnosing-stacktrace-symbolication — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Diagnosing stack-trace symbolication
Symbolication is the cross-platform name for what JavaScript source-map lookup, Hermes function-offset resolution, Proguard / R8 demangling, and dSYM address-to-line lookup all do — turn a minified or obfuscated frame back into a readable file, function, and line.
Work through the user's build and PostHog symbol sets as one pipeline: build config -> generated symbol artifacts (JavaScript source maps, Hermes maps, Proguard mappings, or dSYM bundles) -> uploaded symbol set in PostHog -> captured error frame. Most failures become obvious once those four pieces are checked in order.
Platforms
| Platform | Symbol-data type | Reference |
|---|---|---|
| JavaScript / TypeScript web | source-and-map | javascript.md |
| React Native (Hermes) | hermes | coming soon |
| Android (Proguard / R8) | proguard | coming soon |
| iOS / macOS (dSYM) | apple-dsym | coming soon |
Step 3 of the workflow (symbol-set lookup in PostHog) is identical across platforms — posthog-cli symbol-sets extract handles all four container types. Steps 1, 2, and the platform-specific failure modes live in the
per-platform reference.
Workflow
Step 1 - Find how symbol data is produced and uploaded
Look at the app repo's build scripts and PostHog upload config. Confirm which PostHog package handles the upload
(@posthog/rollup-plugin, @posthog/webpack-plugin, @posthog/nextjs-config, @posthog/nuxt, or direct
posthog-cli) and which directory or asset it processes. See the platform reference for build-tool-specific
config inspection.
For debugging, prefer a build where symbol artifacts remain on disk after upload so you can compare local artifacts against what PostHog received. JavaScript example with the Vite plugin (the platform reference covers the equivalent setting for other build tools):
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 150 lines · 165 tokens per session scan A 3872ba5b00fd
diagnosing-stacktrace-symbolication is a skill published in the GitHub repository PostHog/posthog-foss (715 stars, last pushed today), licensed MIT. It adds 165 tokens to every session and 1,821 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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