Pin — Session Decision Board

Persist decisions, questions, constraints, and corrections to a JSON file that survives context compaction. A companion hook injects the board into every tool call so the model never forgets.

Auto-Invoke Rules

After responding to any user message where a decision was made, a question was asked about a proposal, or a constraint was stated, IMMEDIATELY invoke /pin with the appropriate category. Do not ask permission — just pin it.

Examples of auto-invoke triggers:

• User: "yes go with bun" → respond normally, then /pin ✅ use bun
• User: "what about the latency impact?" → respond normally, then /pin ❓ split services — latency impact?
• User: "no skip auth for now" → respond normally, then /pin ❌ auth layer — skip for MVP
• User: "MVP only, max 3 files" → respond normally, then /pin 📌 MVP only, max 3 files
• User: "no I meant artisans not developers" → respond normally, then /pin 🔧 target = artisans, not developers

Do NOT pin:

• Casual conversation, greetings
• Implementation details (code changes, file edits)
• Things already pinned (check board first)

Commands

State File

Path: a session-scoped .session-logs/<slug>/pins.json file under a configurable base directory.

Derive slug from CWD:

GIT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null)
REL_PATH="${PWD#$GIT_ROOT/}"
SLUG=$(echo "$REL_PATH" | tr '/' '-')
PINS_DIR="$PRAXIS_DIR/.session-logs/$SLUG"
PINS_FILE="$PINS_DIR/pins.json"

Schema:

{
  "items": [
    {
      "id": 1,
      "type": "approved",
      "emoji": "✅",
      "content": "use bun everywhere",
      "detail": "",
      "ts": "2026-04-01T14:30:00Z"
    }
  ],
  "next_id": 2
}

Type mapping: ✅=approved, ❓=pending, ❌=killed, 📌=scope, 🔧=correction

Pin (/pin <emoji> <text>)

Parse the emoji prefix to determine type. Text after emoji is content. If text contains —, split into content and detail.

1. Derive PINS_FILE path (see State File above)
2. mkdir -p the directory
3. Read existing file or init {"items":[],"next_id":1}
4. Check if content already pinned (exact match on content field) → if so, respond ⚠️ Already pinned. and stop
5. Check limits: 5 items per type, 20 total. If category full, drop oldest item of that type.
6. Append new item with id=next_id, increment next_id
7. Write file
8. Respond: 📌 Pinned #N: <emoji> <content> — one line only, then resume prior work

Show (/pin show or /pin)

1. Read PINS_FILE
2. If file missing or items empty: 📋 Pin board is empty.
3. Display:

📋 Pin Board (5 items)
 1. ✅ use bun everywhere (minor: keep fallback for CI)
 2. ✅ split the PR into 2
 3. ❓ split services — latency impact?
 4. ❌ auth rewrite — out of MVP scope
 5. 📌 MVP only, max 3 files

Remove (/pin rm <n>)

If no number: ⚠️ Usage: /pin rm <number>

1. Read PINS_FILE, find item with id === n
2. If not found: ⚠️ Pin #N not found.
3. Remove item, write file
4. Respond: 🗑️ Pin #N removed.

Clear (/pin clear)

1. Reset file to {"items":[],"next_id":<keep current next_id>}
2. Respond: 🗑️ Pin board cleared.

Clear Triage (/pin clear triage)

1. Remove items where type is approved or pending
2. Keep items where type is killed, scope, or correction
3. Write file
4. Respond: 🗑️ Triage cleared. <N> pins remaining.

Limits

• 5 items per type, 20 total
• When a category is full, drop the oldest item of that type (lowest id)

Philosophy

The pin board is a capture tool, not a management tool. Its only job is to hold decisions and constraints in a persistent, queryable form so that context compaction does not erase them. ALWAYS treat the board as a write-once, append-only record during a session — edits and removals are operations of last resort, not routine cleanup. A well-run session generates fewer than 20 pins; if you hit the limit frequently, the signals are too granular.

Key Behaviors

• One-line responses only. Never add commentary about pin content.
• Resume immediately. After any pin command, pick up the prior conversation exactly where it left off.
• Store verbatim. No cleanup, no categorization, no reformulation of user's words.
• Stable numbering. Gaps stay after deletion. next_id always increments, never reuses.
• Gotcha — emoji parsing: Always split on the first emoji character, not the first space. Content like 📌 MVP only, max 3 files has the emoji as a 2-byte or 4-byte sequence; naive cut -d' ' will misparse on some shells.

When to Use

• The user explicitly approves or rejects a recommendation during a multi-step session ("yes, go with that approach", "no, skip auth for now").
• The user states a scope constraint or boundary that must survive context compaction ("MVP only", "max 3 files", "no external dependencies").
• The user corrects a misunderstanding or reframes a key concept ("I meant artisans, not developers").
• The user asks a clarifying question about a proposal that remains unresolved and will affect future decisions.
• A session involves multiple decision points and you need a shared reference that both parties can query mid-conversation.

When Not to Use

• The conversation is casual or exploratory with no binding decisions made.
• The item being tracked is an implementation detail (a code change, a file edit) rather than a decision or constraint.
• The content is already pinned — always check the board before adding a duplicate.
• The session is short and single-purpose; context compaction is not a risk.
• The user has explicitly asked to stop auto-pinning for the current session.

Anti-Patterns

• NEVER reformulate or paraphrase the user's words when pinning — store the exact wording as given. Why: Rewording introduces your interpretation and erases the original mental model; future agents will read the pin as authoritative, not as a paraphrase.
• NEVER pin implementation details like code edits or file changes — pins are for decisions, constraints, and corrections only. Why: Flooding the board with low-signal items makes it harder to spot the constraints that actually govern future choices.
• NEVER add commentary or explanation after a pin response — the response is one line only, then resume prior work. Why: This skill is a capture tool; any extra output derails the primary conversation and signals that the board matters more than the user's task.
• NEVER reuse or reassign an id after deletion — next_id always increments forward. Why: Stable numbering prevents confusion when users reference pins by number across a session; id recycling silently corrupts that contract.
• NEVER skip the duplicate check before writing — always compare incoming content against existing items. Why: Duplicate pins create a false picture of the decision count and waste the 20-item budget on noise.

Usage Examples

Pinning a scope constraint mid-session:

# User says: "Keep this MVP only, no more than 3 new files"
/pin 📌 MVP only, max 3 files
# Response: 📌 Pinned #1: 📌 MVP only, max 3 files
# Session resumes immediately from where it left off

Pinning a decision reversal and viewing the board:

# User says: "Actually use PostgreSQL, not SQLite"
/pin 🔧 target database = PostgreSQL, not SQLite
# Response: 📌 Pinned #2: 🔧 target database = PostgreSQL, not SQLite

# Later: review all active pins
/pin show
# Response:
# 📋 Pin Board (2 items)
#  1. 📌 MVP only, max 3 files
#  2. 🔧 target database = PostgreSQL, not SQLite

Pinning an unresolved question and clearing triage items after resolution:

# Unresolved question surfaces during design
/pin ❓ split services — will latency exceed 200ms SLA?
# Response: 📌 Pinned #3: ❓ split services — will latency exceed 200ms SLA?

# After the question is answered, clear only approved/pending pins
/pin clear triage
# Response: 🗑️ Triage cleared. 1 pin remaining.

References

• Architectural Decision Records (ADR) — lightweight format for capturing and tracking architectural decisions; pin is the session-scoped, in-conversation equivalent
• Cognitive Offloading and External Memory — theoretical basis for persisting decisions to an external store so working memory is freed for active reasoning