echo

A tool for finding information from earlier coding sessions.

In plain words
What is it for?
Recalling previous work, checking whether something was built, or continuing an earlier topic.
Why use it?
Past decisions and unfinished work are easy to lose between sessions. It helps recover that context when the user asks what happened before.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/cwinvestments/memstack/echo
Any agent
npx skills add cwinvestments/memstack --skill echo
Clone the repo
git clone --depth 1 https://github.com/cwinvestments/memstack

Made for: Claude Code, Codex.

Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,752 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00035 $0.01752
Opus 5 $0.00017 $0.00876
Sonnet 5 $0.00007 $0.00350
Haiku 4.5 $0.00003 $0.00175

Measured yesterday against content hash 22b6db3cb2d3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

echo 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 yesterday.

The scan reads SKILL.md. This mod also ships 2 executable files (index-sessions.py, search.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/echo/SKILL.md · 161 lines

How it starts

The opening of the file, as written. The whole thing — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.

🔊 Echo — Searching the Archives...

Recall information from past CC sessions using semantic vector search.

Activation

When this skill activates, output:

🔊 Echo — Searching the archives...

Then execute the protocol below.

Context Guard

Context Status Priority
User says "recall", "remember", "last session", "what did we" ACTIVE — search memory P1
User asks about past work explicitly ("did we build X?") ACTIVE — search memory P1
User says "continue from" or "resume" a past topic ACTIVE — search memory P2
User is describing NEW work to do ("build X", "add Y") DORMANT — this is new work, not recall
User mentions "memory" in code context (RAM, variables) DORMANT — technical term, not MemStack recall
User mentions a project name in present tense ("work on X") DORMANT — forward-looking, not recall
User says "save" or "log" (Diary/Project territory) DORMANT — Diary or Project skill handles writing

Anti-Rationalization

If you're thinking any of these, STOP — you're about to skip the protocol:

You're thinking... Reality
"I remember this from earlier in the conversation" You don't persist. Earlier context may be compacted. Run the search.
"I can just summarize from what I know" You know nothing from prior sessions. The database does. Search it.
"The user probably doesn't need exact details" Users ask Echo for specifics — dates, decisions, file paths. Run all steps.
"Vector search seems slow, I'll skip to SQLite" Vector search returns the best results. Always try it first.
"I found one result, that's probably enough" Run ALL steps (vector + SQLite + insights). One source misses context another catches.
"The keywords are too vague to search" Search anyway. Vague queries still return useful semantic matches.

Protocol

Step 1: Semantic Vector Search (primary)

Try LanceDB vector search first for best-quality results:

python "$MEMSTACK_PATH/skills/echo/search.py" "<keywords>" --top-k 5

Read the full file on GitHub · 161 lines

Files

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.

Changes

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.

  1. yesterday First seen · 161 lines · 35 tokens per session scan A 22b6db3cb2d3

Subscribe to this mod's changes

echo is a skill published in the GitHub repository cwinvestments/memstack (417 stars, last pushed 5d ago), licensed MIT. It adds 35 tokens to every session and 1,752 once invoked, about $0.0002 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 2026-08-30.

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