Pp Substack Reader

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Substack Reader — Printing Press CLI

Prerequisites: Install the CLI

This skill drives the substack-reader-pp-cli binary. You must verify the CLI is installed before invoking any command from this skill. If it is missing, install it first:

1. Install via the Printing Press installer. It defaults binaries to $HOME/.local/bin on macOS/Linux and %LOCALAPPDATA%\Programs\PrintingPress\bin on Windows:

   npx -y @mvanhorn/printing-press-library install substack-reader --cli-only

2. Verify: substack-reader-pp-cli --version
3. Ensure the reported install directory is on $PATH for the agent/runtime that will invoke this skill.

If the npx install fails (no Node, offline, etc.), fall back to a direct Go install (requires Go 1.26.6 or newer). This installs into $GOPATH/bin (default $HOME/go/bin), so add that directory to $PATH instead:

go install github.com/mvanhorn/printing-press-library/library/media-and-entertainment/substack-reader/cmd/substack-reader-pp-cli@latest

If --version reports "command not found" after install, the runtime cannot see the binary directory on $PATH. Do not proceed with skill commands until verification succeeds.

Substack Reader archives whole publications into a local SQLite mirror you can search, SQL-query, and read offline. Free posts need no login; paid posts you're entitled to unlock with your own session cookie — never redistributed, always opt-in. Unlike every other Substack tool it builds a corpus that compounds instead of fetching live per call.

When to Use This CLI

Use Substack Reader when you want a durable, searchable local copy of one or more Substack publications for reading, agent workflows, or analysis — especially reading a specific post's full text or searching across newsletters offline. It is the right tool when you value a corpus that compounds over live per-call fetching.

Anti-triggers

Do not use this CLI for:

• Do not use it to publish, schedule, or manage a Substack you own (this is read-only) — use the Substack web app or a publishing tool.
• Do not use it to bulk-scrape or redistribute paid content you are not entitled to — it reads only your own entitled content, on demand.
• Do not use it to manage subscribers, payments, or analytics for your own publication.

Unique Capabilities

These capabilities aren't available in any other tool for this API.

Local corpus that compounds

• archive — Archive a whole Substack publication into a local SQLite mirror you can read, search, and query offline — no other Substack tool builds a persistent corpus. --limit 0 walks the whole archive; when a run stops at --limit instead of exhausting the archive, the output says so (JSON carries "exhausted": false) — never treat a limit-stopped run as a complete archive.

  Reach for this to turn a live newsletter into a durable, queryable knowledge base instead of re-fetching every time.

  substack-reader-pp-cli archive astralcodexten --limit 0

• sql — Run read-only SQL over your local Substack corpus for arbitrary analytics — post cadence, audience mix, longest posts — from data you've already archived.

  Reach for this for ad-hoc analytics over what you've archived, without re-fetching or writing code.

  substack-reader-pp-cli sql "SELECT json_extract(data,'$.audience') AS audience, COUNT(*) FROM resources WHERE resource_type='posts' GROUP BY audience"

Entitlement-aware reading

• read — Read one or more posts' full text in a single call; free posts keyless, and paid posts you subscribe to via your own session cookie — with an honest 'preview only, you're not entitled' signal. With several posts, JSON mode emits an array of envelopes (a failed post becomes a {"post", "error"} entry and the rest still return); a single post keeps the single-object envelope.

  Use to pull posts' full text into an agent workflow — several slugs in one call, no shell loop — respecting exactly what the user is entitled to.

  substack-reader-pp-cli read astralcodexten/open-thread-441
  substack-reader-pp-cli read astralcodexten/slug-one astralcodexten/slug-two --agent --select slug,subtitle

Topic & comparative intelligence

• digest — A time-windowed digest across every publication in your local corpus — what's new since you last synced, ranked, in one view.

  Use as a personal 'what did I miss across my newsletters' briefing.

  substack-reader-pp-cli digest --since 7d

• author-compare — Compare two publications' cadence, topics, and free/paid mix from the local corpus.

  Use to size up a newsletter before subscribing, or to study what a successful author publishes.

  substack-reader-pp-cli author-compare astralcodexten blog.bytebytego.com

Command Reference

categories — Browse Substack's publication categories

• substack-reader-pp-cli categories browse — List publications in a category
• substack-reader-pp-cli categories list — List all Substack categories

publications — Discover Substack publications

• substack-reader-pp-cli publications <query> — Search Substack publications by name (best-effort; may return few results anonymously)

Finding the right command

When you know what you want to do but not which command does it, ask the CLI directly:

substack-reader-pp-cli which "<capability in your own words>"

which resolves a natural-language capability query to the best matching command from this CLI's curated feature index. Exit code 0 means at least one match; exit code 2 means no confident match — fall back to --help or use a narrower query.

Recipes

Build a searchable corpus

substack-reader-pp-cli archive astralcodexten --limit 0 && substack-reader-pp-cli search "prediction markets"

Mirror a whole publication (--limit 0 = no cap) then search it offline with FTS ranking. Compact/agent search hits carry key fields plus a bounded snippet — never full post bodies; use read (or --select) when you want a hit's full text.

Narrow a large post to fields

substack-reader-pp-cli read astralcodexten/open-thread-441 --agent --select title,post_date,audience,body_html

Pull only the fields an agent needs from a verbose post object.

Read several posts in one call

substack-reader-pp-cli read astralcodexten/slug-one astralcodexten/slug-two astralcodexten/slug-three --agent --select slug,subtitle,audience

Batch-read a list of slugs without a shell loop; JSON mode returns an array of post envelopes, and one bad slug doesn't sink the rest.

Audience mix analytics

substack-reader-pp-cli sql "SELECT json_extract(data,'$.audience') AS audience, COUNT(*) FROM resources WHERE resource_type='posts' GROUP BY audience"

Read-only SQL over the local corpus for arbitrary analytics.

Auth Setup

Free and public posts are keyless — zero setup. Every command works the moment the CLI is installed: no account, no API key, nothing to configure. Authentication only ever matters for paid posts.

There is one optional layer: your own Substack session cookie (substack.sid). Substack decides entitlement server-side from the session you present, so handing the reader your own cookie unlocks exactly the paid posts you already subscribe to — and nothing else. This is your own cookie, never an API key, it is never required for free content, and one cookie covers every subscription on your account (entitlement is account-level, not per-publication).

Provide it any of these three ways (first hit wins):

# 1. Environment variable — the bare substack.sid value...
export SUBSTACK_SESSION="s%3A..."
# ...or the whole cookie fragment, if that is what you copied
export SUBSTACK_SESSION="substack.sid=s%3A..."

# 2. A JSON cookie file at the default config-dir path
#    (~/.config/substack-reader-pp-cli/cookie.json on the platform default).
#    The directory does not exist on a clean install — create it first.
mkdir -p ~/.config/substack-reader-pp-cli && chmod 700 ~/.config/substack-reader-pp-cli
echo '{"substack.sid":"s%3A..."}' > ~/.config/substack-reader-pp-cli/cookie.json
chmod 600 ~/.config/substack-reader-pp-cli/cookie.json

# 3. The same JSON cookie file, kept anywhere on disk
export SUBSTACK_COOKIE_FILE=/path/to/substack-cookie.json

Precedence is SUBSTACK_SESSION, then SUBSTACK_COOKIE_FILE, then the default config-dir file. SUBSTACK_COOKIE_FILE is authoritative once set: a missing, unreadable, unparseable or substack.sid-less file there is a hard error, never a silent fall-through to a stale default. The default config-dir file is best-effort: a file that exists but cannot be read or parsed degrades to anonymous with a warning, while an absent file — or one that parses but carries no substack.sid — degrades to anonymous silently. The config directory itself is relocatable with SUBSTACK_READER_CONFIG_DIR or SUBSTACK_READER_HOME.

Getting the cookie out of your browser. Open DevTools → Application → Cookies → https://substack.com, and copy the value of substack.sid. Only substack.sid is needed — connect.sid is not. Copy it rather than retyping it: a single capital-I/lowercase-l slip yields a cookie that silently reads as anonymous.

With the MCP server. The MCP server resolves the session exactly as the CLI does, so the cookie file in the config directory needs no env block at all — save cookie.json and the server picks it up. If you would rather configure it explicitly, set either variable under env in your Claude Desktop config (the MCPB bundle prompts for it as an optional field).

Your cookie stays yours. It never leaves your machine except to Substack itself, is masked in every output path so scripted runs cannot leak it, and is never redistributed. Any copy the CLI persists is written 0600 under a 0700 parent, and a group/other-readable cookie file earns a warning.

Failure is honest, never silent. With no session, a paid post returns Substack's public preview and says so: access: preview, authenticated: false, full: false, plus a preview only (N of ~M words) — no session configured line on stderr. A downgrade is always visible; it never passes itself off as a full read.

Run substack-reader-pp-cli doctor to verify setup.

Agent Mode

Add --agent to any command. Expands to: --json --compact --no-input --no-color --yes.

• Pipeable — JSON on stdout, errors on stderr

• Filterable — --select keeps a subset of fields. Dotted paths descend into nested structures; arrays traverse element-wise. Critical for keeping context small on verbose APIs:

  substack-reader-pp-cli categories list --agent --select id,name,status

• Previewable — --dry-run shows the request without sending

• Offline-friendly — sync/search commands can use the local SQLite store when available

• Non-interactive — never prompts, every input is a flag

• Read-only — do not use this CLI for create, update, delete, publish, comment, upvote, invite, order, send, or other mutating requests

Response envelope

Commands that read from the local store or the API wrap output in a provenance envelope:

{
  "meta": {"source": "live" | "local", "synced_at": "...", "reason": "..."},
  "results": <data>
}

Parse .results for data and .meta.source to know whether it's live or local. A human-readable N results (live) summary is printed to stderr only when stdout is a terminal AND no machine-format flag (--json, --csv, --compact, --quiet, --plain, --select) is set — piped/agent consumers and explicit-format runs get pure JSON on stdout.

Paths and state

Agents should treat the CLI's path resolver as part of the runtime contract:

• Use --home <dir> for one invocation, or set SUBSTACK_READER_HOME=<dir> to relocate all four path kinds under one root.

• Use per-kind env vars only when a specific kind must diverge: SUBSTACK_READER_CONFIG_DIR, SUBSTACK_READER_DATA_DIR, SUBSTACK_READER_STATE_DIR, SUBSTACK_READER_CACHE_DIR.

• Resolution order is per-kind env var, --home, SUBSTACK_READER_HOME, XDG (XDG_CONFIG_HOME, XDG_DATA_HOME, XDG_STATE_HOME, XDG_CACHE_HOME), then platform defaults.

• config contains settings like config.toml and profiles. data contains credentials.toml, data.db, cookies, and auth sidecars. state contains persisted queries, jobs, and teach.log. cache contains regenerable HTTP/cache files.

• Stored secrets live in credentials.toml under the data dir. Existing legacy config.toml secrets are read for compatibility and leave config.toml on the first auth write.

• Run substack-reader-pp-cli doctor --fail-on warn to surface path and credential-location warnings. agent-context exposes a schema v4 paths block for agents that need the resolved dirs.

• For MCP, pass relocation through the MCP host config. The MCP binary does not inherit CLI flags:

  {
    "mcpServers": {
      "substack-reader": {
        "command": "substack-reader-pp-mcp",
        "env": {
          "SUBSTACK_READER_HOME": "/srv/substack-reader"
        }
      }
    }
  }

Fleet precedence: an inherited per-kind env var overrides an explicit --home for that kind. Use SUBSTACK_READER_HOME or per-kind vars as durable fleet levers, and use --home only for a single invocation. Relocation is not reversible by unsetting env vars; move files manually before clearing SUBSTACK_READER_HOME, or doctor will not find credentials left under the former root.

Automatic learning

This CLI ships a self-capturing learning loop. The CLI does its own bookkeeping: every invocation is journaled locally, a failed flag followed by a corrected retry auto-derives a flag_alias candidate, and a teach on a query family without a playbook auto-synthesizes a playbook_candidate from the session's journal. Your job is judgment only: recall first, act on surfaced candidates, teach the final answer, playbook amend when you observe a correction. You never record failures by hand.

Step 1: recall before any discovery

Before list/search/drill commands on a new user question, run:

substack-reader-pp-cli recall "<user's question>" --agent

The response envelope:

{
  "query": "...",
  "normalized": "<normalized form>",
  "query_entities": ["..."],
  "found": true | false,
  "match_score": 0.0,
  "results": [
    { "resource_id": "...", "resource_type": "...", "venue": "...",
      "confidence": 2, "entity_match": "exact|partial|unknown",
      "source": "taught|preseed|pattern", "warnings": ["..."] }
  ],
  "mismatches": [ /* only when --debug-mismatches */ ],
  "warnings": [ /* top-level */ ],
  "candidates": [
    { "id": 12, "class": "flag_alias | playbook_candidate",
      "summary": "...", "sightings": 3, "last_seen": "...",
      "rationale": "...",
      "next_action": ["<trial command>", "substack-reader-pp-cli learnings confirm 12"] }
  ],
  "playbook": {
    "query_family": "...",
    "playbook": {
      "steps": [ { "cmd": "<command with {slot} substitution>", "purpose": "..." } ],
      "entity_slots": ["$ENTITY"],
      "expected_tool_calls": 3
    },
    "slots_resolved": { "$ENTITY": { "token": "<live token>", "canonical": "<canonical>" } },
    "notes": "<workarounds + gotchas for this query family>"
  },
  "notes": "<duplicate surface for non-playbook callers>"
}

Empty-store short-circuit: if the store has no learnings, playbooks, or candidates yet (recall finds nothing and learnings list and learnings candidates are both empty), skip recall for the rest of this session instead of taxing every query; resume recall-first once something has been taught.

Step 2: decision tree

Read candidates, playbook, notes, results[0], and warnings in that order:

if Candidates present (warnings include "candidates_present"):
    -> candidates are try-then-confirm, never facts. Follow each candidate's
       two-step next_action verbatim: run the trial command first, then run
       `learnings confirm <id>` only after the trial verified the behavior.
       Reject a wrong candidate with `learnings reject <id>`.
    -> NEVER re-teach something recall surfaced as a candidate; confirm or
       reject that candidate instead of teaching a duplicate.
    -> candidates ride alongside playbooks and resource hits, not instead of
       them; continue with the branches below after acting on them.

if Playbook present:
    -> READ Playbook.notes verbatim FIRST (workarounds + gotchas the CLI surface doesn't expose)
    -> replay Playbook.steps in order, substituting Playbook.slots_resolved entries
       for the entity slot tokens. If a step's slot is unresolved, fall back to
       discovery for that step only.
    -> the Playbook's expected_tool_calls is a budget; if you find yourself running
       materially more, record the divergence via `substack-reader-pp-cli playbook amend`
       at end-of-session.

elif Notes present (no Playbook):
    -> read Notes verbatim before any discovery step; they carry known gotchas
       for this query family even when no structured choreography exists yet.

elif Found AND Results[0].EntityMatch == "exact" AND Results[0].Confidence >= 2:
    -> skip discovery; fetch live data for Results[*].ResourceID in parallel

elif Found AND Results[0].EntityMatch == "partial":
    -> candidate hint, NOT a hit; read the resource title to validate before trusting

elif (any row in Mismatches[] when --debug-mismatches was passed):
    -> treat as cold start; the stored learning is for a different entity
       (different canonical resolved from query_entities)

else:  // Found == false, no playbook, no notes
    -> cold start; run discovery normally; teach the answer afterward (Step 4).
       If the family has no playbook yet, that teach auto-synthesizes a
       playbook candidate from this session's journal - you do not need to
       record one by hand.

Playbook and Notes are orthogonal to the per-resource path. A recall response can carry both a Playbook AND a Results[] hit - use both: the Playbook tells you which choreography to run; the resource hits short-circuit specific steps. Default to skipping mismatches; pass --debug-mismatches only when investigating cold-start surprises.

Candidate judgment details: learnings confirm <id> prints the candidate's full payload before materializing it - check that the printed payload matches the behavior you verified. learnings reject <id> tombstones the derivation signature so the same candidate does not resurface. The envelope carries only the few candidates worth acting on now; substack-reader-pp-cli learnings candidates lists the full open set.

Graceful degradation: if learnings confirm is an unknown command, you are driving an older binary - ignore the candidates guidance and follow the rest of the protocol.