lisa-posthog-access

name	lisa-posthog-access
description	Vendor-neutral access layer for…
allowed-tools	["Bash","Read","Skill"]

PostHog Access: $ARGUMENTS

Single chokepoint for PostHog operations. Caller skills and rules MUST NOT call mcp__posthog__* tools or PostHog REST directly.

Invocation Contract

operation: query project_id:<ID> payload:{...}
operation: insights project_id:<ID>
operation: persons project_id:<ID> [query:<QUERY>]
operation: events project_id:<ID> [after:<ISO>] [before:<ISO>]

Return parsed JSON in a <result> block.

Substrate Selection

Probe in order — the ordering is the shared credential-substrate-precedence contract, not a PostHog-local choice. The first tier that is ready and identity-matches the configured project is used; a substrate authenticated against a different project is skipped, never used.

1. Tier 1 — configured-provider substrate: POSTHOG_PERSONAL_API_KEY bearer token against the configured PostHog host, resolved through lisa-secrets-access.
2. Tier 2 — interactive MCP fallback: PostHog MCP, if available and authenticated. Used when tier 1 is genuinely unavailable: no POSTHOG_PERSONAL_API_KEY, no REST adapter for the operation, or a PostHog outage.

PostHog documents personal API keys and bearer authentication, and the same key works interactively and headlessly — which is why it leads. The REST tier uses:

POSTHOG_HOST=${POSTHOG_HOST:-https://app.posthog.com}

# Resolve the key through the chokepoint before giving up on the environment.
# `$POSTHOG_PERSONAL_API_KEY` is the documented fallback, not the only rung:
# without this, a project that keeps its credentials in Bitwarden, Doppler, or
# AWS has no tier 1 path at all and silently resolves through the interactive
# MCP — the exact divergence `credential-substrate-precedence` exists to remove.
read_posthog_key() {
  [ -n "${POSTHOG_PERSONAL_API_KEY:-}" ] && { echo "$POSTHOG_PERSONAL_API_KEY"; return; }
  #
  # Ordered across trusted machine-managed substrates, ending at the installed
  # package. Checkout-local paths are deliberately absent: a familiar generated
  # destination is still repository-controlled executable code. The plugin
  # rungs are the floor: `resolve-secret.mjs` ships beside this skill, so a rung
  # pointing at it is reachable from anywhere the plugin itself is installed.
  # Without one, a consumer repository that vendors none of the leading paths
  # never reaches a resolver at all — the ladder exits without having asked
  # anything, which is what pushed agents into improvising their own credential
  # lookups. This LADDER is identical in every skill that resolves a credential
  # and `credential-resolver-ladder` fails if any copy diverges. Only what
  # happens AFTER the ladder may differ between them.
  # Execute only machine-managed plugin/package resolvers. Checkout-local
  # candidates are repository-controlled code, not trusted merely by path.
  local candidates=()
  if [ -n "${CLAUDE_PLUGIN_ROOT:-}" ]; then
    candidates+=("$CLAUDE_PLUGIN_ROOT/skills/lisa-secrets-access/scripts/resolve-secret.mjs")
  fi
  if [ -n "${PLUGIN_ROOT:-}" ]; then
    candidates+=("$PLUGIN_ROOT/skills/lisa-secrets-access/scripts/resolve-secret.mjs")
  fi
  # Last rung deliberately needs no environment variable: an agent that was
  # never handed a plugin root still has the installed package to fall back on.
  candidates+=(node_modules/@codyswann/lisa/plugins/lisa/skills/lisa-secrets-access/scripts/resolve-secret.mjs)

  local resolver
  local tried=()
  for resolver in "${candidates[@]}"; do
    tried+=("$resolver")
    if [ -f "$resolver" ]; then
      local via_lisa
      via_lisa=$(node "$resolver" get POSTHOG_PERSONAL_API_KEY 2>/dev/null) \
        && [ -n "$via_lisa" ] && { echo "$via_lisa"; return; }
      # Empty/error means this substrate had no answer; try the next trusted one.
    fi
  done
  # Name every path. A bare `return 1` sends the next reader hunting for a
  # resolver they cannot see the absence of; the enumeration turns that into a
  # seconds-long diagnosis. Paths and store coordinates only — never any
  # resolved value, on any path.
  echo "Error: could not resolve POSTHOG_PERSONAL_API_KEY through lisa-secrets-access." >&2
  echo "Tried, in order (relative paths are from $PWD):" >&2
  printf '  %s\n' "${tried[@]}" >&2
  return 1
}

posthog_api() {
  local path="$1"
  local method="${2:-GET}"
  local body="${3:-}"
  local key
  key=$(read_posthog_key) || {
    echo "Error: no PostHog key. Set POSTHOG_PERSONAL_API_KEY, or store it as" >&2
    echo "POSTHOG_PERSONAL_API_KEY in this project's secrets provider." >&2
    return 1
  }
  local args=(-sS -X "$method" -H "Authorization: Bearer $key")
  [ -n "$body" ] && args+=(-H "Content-Type: application/json" --data-binary "$body")
  curl "${args[@]}" "${POSTHOG_HOST%/}/api${path}"
}

If neither tier works, fail with:

Error: no PostHog access substrate available. Authenticate the PostHog MCP or set POSTHOG_PERSONAL_API_KEY.

Mutation boundary

Every operation in the Invocation Contract is read-only — analytics retrieval. query is an HTTP POST, but it reads: it submits a query body and changes no PostHog state. So the credential-substrate-precedence guarded fallback for mutating operations (write, read back, assert the tenant from the response, roll back on mismatch) is not engaged here, and a failed tier is simply skipped. Adding a genuinely mutating operation — creating an insight, editing a feature flag — pulls that protocol in: a write of unknown outcome MUST reconcile by read-back before any retry.

Invariants

• Tier order is credential-substrate-precedence: POSTHOG_PERSONAL_API_KEY first, the PostHog MCP as a preserved first-class fallback. Identity-match against the configured project is mandatory on every tier.
• The key is resolved through lisa-secrets-access, with the bare POSTHOG_PERSONAL_API_KEY environment variable as the documented fallback. Never read a second credential store directly.
• POSTHOG_HOST defaults to PostHog Cloud but can point at a self-hosted deployment.
• Consumer skills do not embed PostHog REST paths.