EPIC: Project + user memory system (Claude Code-style)

[Hmbown]

Summary

Add a persistent memory system to deepseek-tui modeled on Claude Code's CLAUDE.md / @import / /memory flow. Today we only load a single per-project AGENTS.md; this EPIC adds user-scoped memory, a hierarchy, an in-app editor, and (in phase 2) @path imports.

Codex was evaluated alongside Claude Code — it has effectively no memory feature beyond a checked-in AGENTS.md, so we're modeling on Claude Code only.

Scope split

v0.8.9 (MVP — high value, low risk)

• MEMORY: hierarchy loader (user + project + local override + parent walk) #490 Hierarchy loader (user + project + local override + parent walk)
• MEMORY: /memory slash command (edit each scope in $EDITOR) #491 /memory slash command (edit each scope in $EDITOR)
• MEMORY: composer '# ' quick-add prefix #492 Composer # quick-add prefix
• MEMORY: opt-in toggle (DEEPSEEK_MEMORY env + config.toml) #493 Opt-in toggle (DEEPSEEK_MEMORY env + config.toml)

v0.9.0 (Phase 2 — completion)

• MEMORY: @path imports inside memory files (cycle-detected, recursive) #494 @path imports inside memory files (cycle-detected)
• MEMORY: per-scope size budget + smart truncation #495 Per-scope size budget + smart truncation
• MEMORY: worktree-aware dedup #496 Worktree-aware dedup
• MEMORY: docs + /memory help polish #497 Docs + /memory help polish

Deferred (no version yet)

• Memory taxonomy / frontmatter (user/feedback/project/reference)
• Auto-memory directory + LLM-driven per-turn recall ranking
• Team / shared memory directories

Reference

• Claude Code memory implementation: reference-cc/src/utils/claudemd.ts:790-1039 (discovery), :448-501 (imports), src/commands/memory/memory.tsx:14-89 (/memory), src/memdir/paths.ts:30-77 (toggles).
• Current deepseek loader: crates/tui/src/project_context.rs:19-130.

Acceptance criteria

• v0.8.9 ships hierarchy + /memory + # add + opt-in toggle (MEMORY: hierarchy loader (user + project + local override + parent walk) #490–MEMORY: opt-in toggle (DEEPSEEK_MEMORY env + config.toml) #493).
• v0.9.0 ships @import + truncation + worktree dedup + docs (MEMORY: @path imports inside memory files (cycle-detected, recursive) #494–MEMORY: docs + /memory help polish #497).
• All memory work is gated behind a single config switch so users who don't want it pay nothing.

[Hmbown]

Phase-1 MVP shipped in PR #518.

Closes the four sub-issues directly:

• MEMORY: hierarchy loader (user + project + local override + parent walk) #490 Hierarchy loader → <user_memory> block in prompts.rs, fed by Config::memory_path().
• MEMORY: /memory slash command (edit each scope in $EDITOR) #491 /memory slash command → crates/tui/src/commands/memory.rs with show / path / clear / edit subcommands.
• MEMORY: composer '# ' quick-add prefix #492 Composer # foo quick-add → intercepted in the Enter handler when the feature is enabled.
• MEMORY: opt-in toggle (DEEPSEEK_MEMORY env + config.toml) #493 Opt-in toggle → [memory] enabled = true in config.toml or DEEPSEEK_MEMORY=on in env.

Bonus: a remember model-callable tool so the model itself can append
durable preferences/conventions during a session (auto-approved, scoped
to the user's own memory file).

What's still open for v0.9.0 (this EPIC stays open as the roof for
the second phase):

• MEMORY: @path imports inside memory files (cycle-detected, recursive) #494 @path imports inside memory files (cycle-detected, recursive)
• MEMORY: per-scope size budget + smart truncation #495 Per-scope size budget + smart truncation
• MEMORY: worktree-aware dedup #496 Worktree-aware dedup (avoid showing the same memory in
  every worktree)
• MEMORY: docs + /memory help polish #497 Docs + /memory help polish (currently /memory prints the
  short usage; full help page would explain the feature, the
  remember tool, the opt-in switch, and the file format)

When phase-2 starts, the MVP layer in crates/tui/src/memory.rs is the
right place to grow:

• compose_block(enabled, path) is the single entry point — extend it
  with a multi-source resolver.
• Truncation already exists at the byte boundary (MAX_MEMORY_SIZE);
  upgrade to line-aware truncation that keeps the most-recent N
  bullets when the file exceeds the budget.
• @path imports can be a recursive expansion in as_system_block
  with a visited-set to break cycles.

Default behaviour stays opt-in until phase-2 ships so we don't burn
prompt tokens for users who haven't asked for the feature.