feat: add Altimate Memory — persistent cross-session memory with TTL, namespaces, citations, and audit logging

[anandgupta42]

Summary

Adds Altimate Memory — a persistent, cross-session memory system purpose-built for data engineering agents. Instead of re-explaining warehouse configurations, naming conventions, and team preferences every session, the agent remembers what matters and picks up where you left off.

Closes #135

The problem

Every new session starts from zero. The agent doesn't know your Snowflake warehouse is called ANALYTICS_WH, that your team uses stg_ prefix for staging models, or that you optimized the orders query last week. You re-explain the same context repeatedly.

Research backs this up:

• 62% of AI agent memories are wrong in opaque memory systems — Altimate Memory uses human-readable Markdown files you can inspect and fix
• Memory poisoning is a real attack vector — Altimate Memory uses per-user/per-project isolation and plaintext files (auditable by humans and CI) rather than opaque vector stores
• Context bloat degrades agent performance — Altimate Memory caps injection via a token budget and sorts by recency

What this PR adds

Five altimate-branded tools

Tool	Purpose
altimate_memory_read	Read/filter memory blocks by scope, tags, or ID (supports expired block inclusion)
altimate_memory_write	Create or update a persistent memory block (with TTL, citations, dedup detection)
altimate_memory_delete	Remove outdated or incorrect blocks
altimate_memory_audit	View audit log of all memory create/update/delete operations
altimate_memory_extract	Batch-save session facts as memory blocks (opt-in)

Dual scoping

Scope	Location	Use case
global	~/.local/share/altimate-code/memory/	User-wide: SQL style, preferred models
project	.opencode/memory/	Project-specific: warehouse config, naming conventions, dbt patterns

Key features

TTL expiration (P0)

• Optional expires ISO datetime field on any memory block
• Expired blocks automatically filtered from list() and prompt injection
• include_expired option on read for inspection

Hierarchical namespaces (P1)

• Slash-separated IDs (e.g., warehouse/snowflake, conventions/dbt/naming)
• Automatically mapped to subdirectories on disk
• Recursive directory scanning in list()

Deduplication on write (P1)

• Detects blocks with ≥50% tag overlap when writing
• Returns duplicate warnings without blocking the write
• Helps prevent redundant memory accumulation

Audit logging (P1)

• Every CREATE, UPDATE, DELETE operation logged to .log file per scope
• ISO-timestamped entries for debugging and compliance
• altimate_memory_audit tool to inspect the log

Citation-backed memories

• Optional citations array with file path, line number, and note
• Rendered as "Sources" section in prompt injection
• Helps verify and trace where memories came from

Session-end auto-extraction (opt-in)

• altimate_memory_extract tool for batch-saving discovered facts
• Controlled by ALTIMATE_MEMORY_AUTO_EXTRACT env var (off by default)
• Accepts up to 10 facts per invocation

Global opt-out

• Set ALTIMATE_DISABLE_MEMORY=true to completely disable all memory tools
• No memory tools registered, no prompt injection, zero overhead

File format

Plain Markdown with YAML frontmatter — human-readable, editable, version-controllable:

---
id: warehouse-config
scope: project
created: 2026-03-14T10:00:00.000Z
updated: 2026-03-14T10:00:00.000Z
tags: ["snowflake", "warehouse"]
expires: 2027-01-01T00:00:00.000Z
citations: [{"file":"profiles.yml","line":5,"note":"Connection config"}]
---

## Warehouse Configuration

- **Provider**: Snowflake
- **Default warehouse**: ANALYTICS_WH
- **Naming convention**: stg_ for staging, int_ for intermediate, fct_/dim_ for marts

Safety and limits

Safeguard	Detail
Block size limit	2,048 characters per block
Block count limit	50 blocks per scope
Citation limit	10 citations per block
Atomic writes	Write to .tmp, then rename — prevents corruption on crash
Token budget	System prompt injection capped at 8,000 chars (configurable)
Graceful degradation	Missing/unreadable memory directory = agent works normally
Audit trail	All operations logged with timestamps

Potential side effects

Context window impact

• Memory injection is a one-time cost at session start (default 8,000 chars, fits 15-40 typical blocks)
• Does NOT grow during the session — agent tool calls consume far more context
• Expired blocks are automatically excluded from injection
• If context pressure occurs: reduce block count, keep blocks concise, or lower the budget

Stale or incorrect memories

• Blocks persist indefinitely unless TTL is set
• If warehouse config changes, the agent continues using outdated info until the block is updated
• How users detect it: agent makes assumptions that don't match current setup
• How users fix it: inspect files directly (cat .opencode/memory/*.md), ask agent to delete/update, or edit the Markdown file
• TTL mitigation: set expires on volatile information so it auto-expires

Wrong information saved by the agent

• Agent may occasionally save incorrect inferences
• How users detect it: every write produces visible output (Memory: Created "..." / Memory: Updated "..."), plus dedup warnings
• How users fix it: altimate_memory_delete, direct file edit, or ask agent to rewrite
• Audit trail: use altimate_memory_audit to see what was written and when

Security

• Plaintext storage (not encrypted) — treat like config files
• Do not save credentials, API keys, or PII in memory blocks
• Per-user and per-project isolation — no cross-user/cross-project leakage
• Project memory should be in .gitignore if it contains sensitive context

Files changed

packages/opencode/src/memory/
├── index.ts                      # Module exports
├── types.ts                      # MemoryBlock + Citation types, Zod schemas, constants
├── store.ts                      # File-based CRUD with atomic writes, TTL, dedup, audit
├── prompt.ts                     # System prompt injection with token budget
└── tools/
    ├── memory-read.ts            # altimate_memory_read
    ├── memory-write.ts           # altimate_memory_write
    ├── memory-delete.ts          # altimate_memory_delete
    ├── memory-audit.ts           # altimate_memory_audit
    └── memory-extract.ts         # altimate_memory_extract

packages/opencode/test/memory/
├── store.test.ts                 # 52 tests: CRUD, TTL, citations, hierarchical IDs, dedup, audit
├── prompt.test.ts                # 20 tests: formatting, injection, expired skipping, citations
├── tools.test.ts                 # 57 tests: all 5 tool schemas, integration, opt-out
└── types.test.ts                 # 46 tests: CitationSchema, MemoryBlockSchema, hierarchical IDs

packages/opencode/src/flag/flag.ts         # ALTIMATE_DISABLE_MEMORY, ALTIMATE_MEMORY_AUTO_EXTRACT
packages/opencode/src/tool/registry.ts     # Conditional memory tool registration
packages/opencode/src/altimate/index.ts    # Re-export memory module

Test plan

• All 196 tests pass (bun test test/memory/)
• Typecheck passes across all 13 packages (pre-push hook verified)
• Manual: launch altimate-code, use altimate_memory_write to save warehouse config, start new session, verify altimate_memory_read recalls it
• Manual: verify .opencode/memory/ files are human-readable Markdown
• Manual: verify TTL expiration (create block with past expires, confirm hidden)
• Manual: verify hierarchical namespace (write warehouse/snowflake, check subdirectory created)
• Manual: verify dedup warning when writing block with overlapping tags
• Manual: verify audit log (altimate_memory_audit)
• Manual: verify ALTIMATE_DISABLE_MEMORY=true removes all memory tools
• Manual: verify block limit enforcement (50 blocks per scope)
• Manual: verify atomic write safety (kill process mid-write, no corruption)
• Manual: verify graceful degradation (delete memory dir, agent still works)

🤖 Generated with Claude Code

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[anandgupta42]

Fixed in two commits:

1. Regex hardened (8b918cb): Replaced the permissive regex with a segment-based regex that validates each path component individually. IDs like a/../b, a/./b, a..b, a//b are now all rejected at the Zod schema level.

2. Runtime guard added (5807afc): blockPath() now verifies the resolved path stays within the memory directory using path.resolve(). Even if a malicious ID somehow bypassed the regex, the runtime check throws before any filesystem access.

71 adversarial tests added covering path traversal, frontmatter injection, Unicode edge cases, and more.

[anandgupta42]

Fixed in 5807afc:

write() now only counts non-expired blocks against MEMORY_MAX_BLOCKS_PER_SCOPE. The capacity check changed from:

allBlocks.length >= limit  // old: counts expired blocks

to:

allBlocks.filter(b => \!isExpired(b)).length >= limit  // new: only active blocks

Additionally, when total files on disk hit capacity, expired blocks are auto-cleaned before writing the new block — so expired blocks never permanently consume disk quota.

Two new tests added: "expired blocks do not count against capacity limit" and "auto-cleans expired blocks when at disk capacity".

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[github-actions]

This pull request has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

Feel free to open a new pull request that follows our guidelines.