Ghost-hunter™

Investigate why your cloud costs spiked, not just what changed.

Ghosthunter uses Claude Opus (hypothesis reasoning) and Claude Sonnet (command execution + output compression) to run a dual-model cost investigation over your cloud billing data. Supports GCP and AWS. Security is enforced in code through a 7-layer validator — the LLM cannot run anything the allowlist does not permit.

Paranoid mode — no cloud access, just a billing CSV. Hypotheses with confidence bars, proposed read-only commands, you stay in control.

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🧪 Early adopter mode — be the first 10

Important

Ghosthunter shipped v1.0.6 to PyPI on April 27, 2026.

It's been hammered against bundled demo scenarios, synthetic billing data, and a 1,000+ test suite. It has not yet been run against production cloud accounts at scale — and we're not going to pretend otherwise.

Paranoid mode is risk-free by construction (it never touches your cloud — just reads a billing CSV and prints commands you run yourself). Run it on a real billing export and tell us what worked, what broke, what surprised you.

What we'll do for the first 10 reporters:

• 🚀 Reply within 24 hours
• 🤝 Walk through your investigation alongside you (free, NDA on request)
• 🐛 Fix any reproducible bug you hit, fast
• 🏆 Credit you in CHANGELOG and on matrixgard.com

How to reach us:

• 📬 Open an issue
• 💌 Email Nash directly — avinash@matrixgard.com

Built in the open. Imperfect on purpose. Looking for the first 10.

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Why Ghosthunter? Comparison vs FinOps tools

Most FinOps tools want admin access and auto-optimize. Ghosthunter does neither. It's an investigator, not an optimizer.

	Ghosthunter	Vantage / CloudHealth / ProsperOps
Access required	None (paranoid mode reads a CSV)	Cross-account IAM role with broad read
Acts on your cloud	Never (read-only by default)	Auto-applies "savings recommendations"
Source code	Open (MIT) — you can audit every command	Closed SaaS
AI model	Claude Opus (reasoning) + Sonnet (execution)	Rules + heuristics, mostly
What it answers	"Why did the bill spike?" (root cause)	"How can you cut 5%?" (optimization)
Pricing	Free CLI; first manual audit free; paid retainer	$X/mo SaaS, often % of cloud spend
Self-hostable	Yes — runs locally, your billing data never leaves your machine in advisor mode	No
Multi-cloud	GCP + AWS (Azure planned)	Multi-cloud, varies by tool

If you want auto-optimization and trust your vendor with admin keys, Vantage and CloudHealth are mature options. If you want to understand your bill without giving anyone admin access, Ghosthunter is the tool.

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Modes at a glance

Mode	When to use	Credentials
Paranoid (advisor) — default	Real work data. Ghosthunter never touches your cloud.	None — zero blast radius
Active	Personal / sandbox projects only. Ghosthunter runs gcloud or aws directly.	Read-only GCP or AWS creds + ~/.ghosthunter/config.toml
Demo	First look, screenshots, offline walkthrough.	None — pre-recorded, no API calls
Audit	Review past investigations.	None — reads ~/.ghosthunter/audit.log

Paranoid mode is the default and the one you should use for anything touching production. It prints the proposed command, you paste the output back — Ghosthunter reasons, you keep control.

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1. Install

Requires Python 3.12+.

# Core (paranoid/advisor mode — no cloud SDK needed)
pip install ghosthunter

# Optional active-mode extras
pip install 'ghosthunter[gcp]'   # GCP active mode (BigQuery + gcloud)
pip install 'ghosthunter[aws]'   # AWS active mode (Cost Explorer via boto3)
pip install 'ghosthunter[all]'   # both providers

After install, the ghosthunter command is on your PATH.

Build from source (contributors)

git clone https://github.com/avinash-matrixgard/ghosthunter
cd ghosthunter
python3.12 -m venv .venv
.venv/bin/pip install -e '.[all]'

Set your API key:

export ANTHROPIC_API_KEY=sk-ant-...

2. Try the demo (no setup)

# Random scenario across all providers
ghosthunter demo

# Specific scenario
ghosthunter demo --scenario=aws_nat_gateway_runaway
ghosthunter demo --scenario=dns_cache_bypass

# Filter by provider
ghosthunter demo --provider=aws
ghosthunter demo --provider=gcp

Replays a bundled investigation end-to-end with no API calls and no cloud access. Takes ~30 seconds.

Same paranoid mode, AWS Cost Explorer CSV.

Bundled scenarios:

• GCP: dns_cache_bypass, nat_egress_runaway, bigquery_full_scan, orphaned_disks, gke_autoscaler_loop
• AWS: aws_nat_gateway_runaway (missing S3 VPC endpoint), aws_s3_lifecycle_miss (bucket with no lifecycle policy)

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3. Paranoid (advisor) mode — the normal path

Ghosthunter sniffs the provider from your billing file's column headers, so --provider is usually unnecessary. Pass it explicitly if you want to override the sniff.

3a. Export your billing data

GCP: run ghosthunter billing-template for the exact commands. Pick one of:

• Option A (recommended): a single rich BigQuery export with service, sku, project, location, date, cost.
• Option B: Console Reports CSV downloads (one per grouping) — merge with multiple -f flags.

AWS: run ghosthunter billing-template --provider=aws. Four paths:

• Option A — Cost Explorer UI CSV downloads grouped by Service, UsageType, Linked Account. Merge with multiple -f flags.
• Option B — aws ce get-cost-and-usage JSON piped to a file.
• Option C — CUR (Cost and Usage Report) CSV from S3 (richest; CUR Parquet is not supported in v1).
• Option D — FOCUS 1.0 CSV (cross-cloud FinOps Foundation spec). Public samples at FinOps-Open-Cost-and-Usage-Spec/FOCUS-Sample-Data let you try Ghosthunter with no cloud account at all.

3b. Run an investigation

# Auto-detects AWS from CUR/CE column headers
ghosthunter investigate \
    -f by-service.csv -f by-usage-type.csv

# Or pick the provider explicitly
ghosthunter investigate \
    --provider=aws -f ce-export.csv

# Or start the chat REPL (mode picker appears unless files are passed)
ghosthunter chat billing*.csv

3c. Drive the investigation

At the > prompt inside the chat REPL:

/list             # show detected cost spikes
/spike 0          # investigate the largest spike

Ghosthunter (via Opus) will:

1. Form 2–4 competing hypotheses with confidence scores
2. Propose a read-only command (gcloud/bq/gsutil for GCP, aws for AWS) to test the top hypothesis
3. Pause and ask you to run it in your own terminal and paste output back
4. Update confidences as evidence comes in
5. Conclude when one hypothesis hits 85% confidence

Controls during an investigation:

Command	Effect
(paste command output)	Feed evidence back to Opus
<free text question>	Ask Opus anything; it answers in the next turn
/note <text>	Inject a note into Opus's context
/hypotheses	Show current confidence bars
/skip	Skip this command, ask Opus to try something else
/spike N	Switch mid-flight to a different spike
/remember <fact>	Save a fact to the memory palace (requires MemPalace — pip install mempalace mcp; silently no-ops otherwise)
/recall <query>	Search memory palace for prior knowledge (same requirement)
/quit	End this investigation, keep chatting
/exit	Exit Ghosthunter

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4. Active mode (sandbox only)

Only safe on a personal/scoped account/project. Requires read-only cloud credentials.

ghosthunter init
# → prompts for provider (gcp/aws), then provider-specific fields

ghosthunter investigate --active

GCP: Ghosthunter queries BigQuery billing export directly, detects spikes, and executes allowlisted gcloud/bq/gsutil commands itself. Requires google-cloud-bigquery installed and GOOGLE_APPLICATION_CREDENTIALS / gcloud auth application-default credentials.

AWS: Ghosthunter queries Cost Explorer via boto3 (one get_cost_and_usage call per window + optional follow-up by USAGE_TYPE), detects spikes, and executes allowlisted aws commands itself. Uses your default credential chain — AWS_PROFILE, env-var keys, SSO, or IAM role. Cost Explorer API is metered at ~$0.01 per request — Ghosthunter shows a one-time banner and persists your acknowledgment in ~/.ghosthunter/config.toml. Each investigation's CE call count lands in the audit log.

# AWS active-mode example
export AWS_PROFILE=dev-sandbox
ghosthunter investigate \
    --active --provider=aws

Do not use active mode against an organization where your credentials have write permission. Use paranoid mode instead.

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5. Other commands

ghosthunter audit                       # past investigations (~/.ghosthunter/audit.log, default 20)
ghosthunter audit --limit 50            # show the last 50 entries
ghosthunter palace status               # check MemPalace memory integration
ghosthunter billing-template            # GCP export recipe
ghosthunter billing-template --provider=aws   # AWS export recipe (4 paths: CE CSV, CE JSON, CUR, FOCUS)

The audit table shows provider, service, result, command count (with CE API call count for AWS active-mode runs), and root cause.

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Security model — what the validator enforces

Every command — whether Opus proposes it in advisor mode or Sonnet executes it in active mode — passes through 7 layers:

1. Fast reject — no ; && || curl wget bash rm or unquoted redirects
2. Allowlist (provider-aware) — must match a specific read-only pattern:
   • GCP: gcloud / bq / gsutil
   • AWS: aws <service> describe-*|list-*|get-*|batch-get-* plus explicit patterns for non-read-shaped reads (aws s3 ls, aws dynamodb scan, aws ce get-*, aws cloudtrail lookup-events, …)
3. Pipe validation — only safe targets (head, wc, jq, grep, sort…)
4. Safety checks — length cap, no encoding tricks. SELECT-only for bq query on GCP. --with-decryption blocked on AWS SSM Parameter Store reads. WRITE_DISGUISED_AS_READ list blocks verbs that look like reads but cause side effects or leak secrets: aws lambda invoke, secretsmanager get-secret-value, ec2 get-password-data, sts assume-role, kms decrypt, Bedrock/SageMaker invoke-*, Athena start-query-execution, etc.
5. Budget limits — 15 commands / $1 / 10 min per investigation
6. Sonnet semantic check — "is this really safe?" final pass
7. Sandboxed execution with provider-scoped env (GCP creds for GCP mode, AWS profile/region/session token for AWS mode; nothing else)

Security is in code, not prompts. Allowlist is the primary gate — if a command doesn't match an allowed pattern, it's blocked regardless of what the LLM claims.

Test suite: 1,000+ tests covering the validator, both providers (GCP + AWS), billing-file parsing (GCP/AWS/FOCUS), investigator loop, CLI, advisor mode, memory palace, and demo replay. Notable files: tests/test_security.py, tests/test_security_aws.py, tests/test_security_aws_full.py, tests/test_investigator.py, tests/test_advisor.py, tests/test_gcp_provider.py, tests/test_aws_provider.py, tests/test_api_retry.py.

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Project layout

src/ghosthunter/
  cli.py              Typer CLI entrypoint + provider sniffing
  chat.py             REPL orchestrator + mode picker
  chat_io.py          prompt_toolkit shared session
  investigator.py     Main investigation loop
  hypothesis.py       Hypothesis dataclass + confidence logic
  evidence.py         Evidence chain
  demo.py             Replay bundled scenarios (GCP + AWS)
  models/
    reasoner.py       Claude Opus client + provider-aware system prompt
    executor.py       Claude Sonnet client (validate + compress)
  security/
    validator.py      7-layer orchestrator, provider-parametrized
    allowlist.py      Dispatcher keyed on command prefix
    allowlist_gcp.py  gcloud/bq/gsutil patterns + bq SELECT-only
    allowlist_aws.py  aws patterns + BASE_READ_RULE +
                      WRITE_DISGUISED_AS_READ blocklist
    blocklist.py      Fast-reject patterns (shell injection)
    pipes.py          Safe pipe validation
  providers/
    base.py           BaseProvider ABC + CostSpike / CommandResult
    gcp.py            GCPProvider — BigQuery billing + gcloud exec
    aws.py            AWSProvider — CE via boto3 + aws CLI exec
    billing_file.py   Advisor mode — parse CE/CUR/Console CSVs
    advisor.py        Print-command / wait-for-paste pseudo-execution
  memory/
    palace.py         Optional MemPalace MCP client (cross-session memory)
sample_data/
  demo_script.json    GCP + AWS bundled scenarios (replay without API)

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Troubleshooting

• ghosthunter: command not found — pip install ghosthunter hasn't run, or your shell PATH doesn't include the install location (pip show ghosthunter to find it). For contributor builds, run pip install -e '.[all]' from the repo root.
• ANTHROPIC_API_KEY not set — export the env var (see install step).
• Opus re-proposes a blocked command — type /skip or /note try a different angle to force a pivot.
• Long JSON output is painful to paste — save to /tmp/out.json and paste the path instead; Ghosthunter reads it directly.
• AWS boto3 is not installed in active mode — pip install boto3 (or pip install 'ghosthunter[aws]' if using an editable install with extras).
• AWS ExpiredToken mid-investigation — your SSO session timed out. aws sso login --profile <x> and retry the command Opus proposed.
• Parquet CUR files — not supported in v1. Ask AWS to also export CSV, or convert locally with parquet-tools csv.

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Known Limitations

These are documented caveats, not bugs. See SECURITY.md for the full threat model.

• Prompt injection via pasted output. Content you paste back from your own terminal is compressed by Sonnet before Opus sees it. Ghosthunter wraps every paste in an <UNTRUSTED_COMMAND_OUTPUT> envelope and instructs Sonnet to treat the contents as factual data only, but the mitigation is trust-based, not rule-based. Don't paste output from untrusted sources (logs from a compromised host, blobs of unknown origin, attacker-supplied data). Every command Opus subsequently proposes still has to pass the 7-layer security validator, so this can waste budget but cannot escalate to arbitrary command execution.
• No secret redaction on disk. If the output you paste contains secrets (env dump, session tokens in log lines, a config file with credentials), those secrets persist to ~/.ghosthunter/chat_history (every prompt-toolkit line you typed) and may end up in ~/.ghosthunter/audit.log / ~/.ghosthunter/palace/ if memory palace is enabled. Redact pastes before handing them to Ghosthunter; delete the relevant files if something slips through.
• Opus can loop on a blocked command. If Opus re-proposes the same rejected command twice, use /skip or /note <hint> to force a pivot. Budget caps keep the blast radius small.
• Per-investigation budget caps. 15 commands / $1 / 10 minutes by default. Hitting any one aborts the investigation. Tune via ~/.ghosthunter/config.toml. AWS active mode additionally tracks Cost Explorer API calls (~$0.01 each) in the audit log.
• Streaming is not implemented. Each Opus turn blocks 5–15 seconds while the API call completes. A live spinner shows the current phase
  • elapsed time so the UI doesn't look frozen.
• CUR Parquet files not supported. Advisor mode reads CSV only (GCP Console exports, AWS CUR CSV, FOCUS 1.0 CSV, Cost Explorer CSV / JSON). Convert Parquet to CSV externally.
• Multi-account AWS Organizations aggregation — one account per run. Point Ghosthunter at each account's billing export separately.
• Azure / OCI / other providers — not shipped. The provider abstraction supports them; implementations are welcome as PRs.
• AWS active mode requires boto3. Install via pip install 'ghosthunter[aws]'. Advisor mode doesn't need it — advisor mode works with a billing file and never calls the AWS API.
• macOS / Linux only in v1. Windows support is untested. The advisor-mode flow should work via WSL; active mode may hit subprocess-environment edge cases.
• Layer 6 is judgment, not rules. The Sonnet-based semantic validator caps damage beyond the regex allowlist but isn't infallible. Layer 2's static allowlist is the primary gate.

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Roadmap

• GCP provider (v1.0)
• AWS provider — advisor + active modes, full allowlist catalog (v1.0)
• Azure provider (v1.2)
• Streaming Opus responses (currently blocks ~5–10s per turn)
• Autonomous mode with strict guardrails (v1.1)
• Multi-account AWS Organizations aggregation
• CUR Parquet support (requires pyarrow)
• Editable install by default

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FAQ

Will Ghosthunter touch my cloud? Not in paranoid mode (the default). It prints proposed read-only commands, you run them in your own terminal, you paste the output back. Active mode is opt-in, sandbox-only, and still passes every command through the 7-layer validator before execution.

How is this different from a FinOps SaaS like Vantage or CloudHealth? Those tools auto-optimize. Ghosthunter investigates. They want admin keys; Ghosthunter wants a CSV. They're closed-source SaaS; Ghosthunter is MIT-licensed CLI you can audit line-by-line. Use both if you have budget. Use Ghosthunter if you don't, or if you can't give your vendor admin access.

Why open source? We're a security practice (MatrixGard). Black-box "AI" tools that touch production cloud aren't a fit for that worldview. Verifiability matters.

Do you store my billing data? Advisor mode keeps everything on your machine. No telemetry, no upload, no analytics. Active mode also runs locally — it queries your cloud directly with credentials you control. Audit logs land in ~/.ghosthunter/audit.log for your own review.

What clouds are supported? GCP and AWS today. Azure provider is planned for v1.2. The provider abstraction (src/ghosthunter/providers/base.py) accepts community PRs.

Can I use my own Anthropic API key? Yes — Ghosthunter reads ANTHROPIC_API_KEY from your env. Per-investigation budget caps (15 commands / $1 / 10 min) keep blast radius small.

How fast can I run my first investigation? With pip install ghosthunter + ghosthunter demo — about 30 seconds. With your own GCP / AWS billing export — about 5 minutes including the export download.

Is there a paid version? The CLI is free forever, MIT-licensed. If you want a manual audit walked-through by a human (the team that built Ghosthunter), see matrixgard.com — first 60-minute audit is free under NDA.

How do I report a security issue? See SECURITY.md. Private vuln reporting via GitHub Security Advisories.

What's the roadmap? See the Roadmap section. AWS provider, Azure provider, streaming Opus responses, multi-account AWS Organizations, autonomous mode with strict guardrails.

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License

See LICENSE.

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Built by MatrixGard

Ghosthunter is built and maintained by MatrixGard — a fractional DevSecOps practice for pre-seed and seed startups.

If you'd rather hire a human to investigate your cloud bill alongside the tool, the first 60-minute audit is free under NDA. Get in touch at matrixgard.com.