# Architecture & Design Decisions

## Knowledge Pipeline: Separate /reflect-logs from /reflect

`/reflect-logs` handles continuous log processing; `/reflect` handles milestone reflections. Different purpose, different cadence — combining them would overcomplicate the milestone skill.

## Knowledge Pipeline: MD5 for reflection state, git SHAs for distill state

Log files may not be committed when reflected on, so MD5 of file content is the right identity. `/distill-best-practices` works across committed repos, so git SHAs are appropriate there.

## Knowledge Pipeline: Pruning happens in /log, not /reflect-logs

`/log` runs most frequently (every session end), so it naturally keeps the log directory clean as a side effect.

## Knowledge Pipeline: /distill-best-practices is interactive

Cross-project convention changes need human judgment. The skill proposes updates and waits for approval before writing.

## Session Logs: Timestamp-based IDs (HHMMSS)

Human-readable, naturally sorted, no external dependencies. Format: `YYYY-MM-DD.HHMMSS.md`.

## Linting: Formatter exit codes vs hook exit codes

Formatter scripts exit 1 on lint errors. The dispatcher hook decides the final exit code (exit 2 for PostToolUse feedback). This separates formatter logic from hook semantics — same scripts work for both PostToolUse and pre-commit.

## Linting: Checkpoint via git hash-object with .pre-lint sidecar

Fast (~1ms), no commits or stash needed, orphan blobs auto-GC'd. Falls back to `cp` outside git repos.

## Linting: Project opt-in via formatter symlinks

Projects opt in by having a `formatters/` directory with symlinks back to canonical scripts. Zero-config, visible in `ls`, no parsing needed. The hook walks up the directory tree to find `formatters/`.

## Skills: Use CLAUDE_PROJECT_ROOT for cross-project path resolution

Skills that reference files outside their own project (e.g., `/distill-best-practices` reading settings.yaml) use `CLAUDE_PROJECT_ROOT` env var instead of hardcoded `~/dev/claude/` or relative `../` paths. Makes skills portable across users. Env var exported in `~/.bashrc`, with runtime fallback (walk up directory tree to find highest CLAUDE.md).

## Skills: settings.yaml paths relative to project root

`settings.yaml` uses relative paths (`projects_dir: projects`) rather than absolute paths. Combined with `CLAUDE_PROJECT_ROOT`, this keeps config portable. The `extra_projects` section handles projects outside the standard `projects_dir` (e.g., `small-scripts` at root level).

## CLAUDE.md: Remove technology-specific sections from root

Ansible and Helm sections removed from root CLAUDE.md — already covered with more detail in `best-practices/ansible.md` and `best-practices/helm.md`. Technology-specific practices belong in best-practices, not root guidelines.

## context-load: Walk upward collecting context files

Walks from cwd upward collecting CLAUDE.md, CONTEXT.md, MEMORY.md, BESTPRACTICES.md at each level. Gives hierarchical context inheritance — highest ancestor provides global guidelines, project dir provides specifics.

## context-load: Dedup via readlink -f

Root CLAUDE.md is a symlink to claude-foundations. Without dedup it would load twice. `readlink -f` resolves all symlinks before comparison.

## context-load: Tree depth 3

Deep enough to show project structure without overwhelming output. Applied at every CLAUDE.md location.

## CONTEXT.md follows MEMORY.md pattern

Thin index + `context/` folder. Consistency with MEMORY.md. CONTEXT.md focuses on active work for agent orientation; MEMORY.md on accumulated learnings.

## Status line: Per-session topic files keyed by session ID

Topic files at `~/.claude/status/<session-id>/claude-topic.txt`. Session ID uniquely identifies each session, allowing multiple concurrent sessions to have independent topics without collisions.

## Status line: Bridge session ID via /tmp file

Claude has no direct access to its own session ID. The status line script writes it to `/tmp/claude-session-id-<md5 of cwd>`, which `set-topic.sh` reads to find the correct per-session topic directory.

## Status line: Pending-topic queue for bootstrap race condition

`set-topic.sh` is called on the first message, before `statusline.sh` has written the session ID file. Instead of erroring, it writes to `/tmp/claude-pending-topic-<hash>`. `statusline.sh` picks this up on its next run via `mv` (atomic, no double-application). Simple and self-healing — statusline already runs after every response.

## Status line: Config must exist in every profile settings file

Each profile (`~/.claude`, `~/.claude-octopus`, `~/.claude-oreillyit`) has its own `settings.json` with no inheritance. The `statusLine` entry and `Bash(~/.claude/status/set-topic.sh:*)` permission must be added to each independently.

## Best practices: One file per topic, not combined mega-documents

api-design.md and llm-code-security.md are separate files despite both being "security-adjacent". API design covers versioning, pagination, idempotency — not just security. Self-contained topic files are independently referenceable and can be loaded selectively by skills and agents.

## Review skills: Read-only output, not auto-edit

/review-plan and /review-spec are read-only (allowed-tools: Read, Glob, Grep). Review output informs the human rather than auto-editing plans/specs. This avoids unintended changes and reduces permission prompts. Both skills load all 5 design/security best practice files upfront — better to over-load context than miss a relevant check.

## Transcript backups: Sonnet (not Haiku) for /log transcript-analysis subagent

Gotcha detection requires judgment about backtracking and failed attempts mid-session. Haiku tends to see only the final outcome and miss the failure mode that led to it. Sonnet in its own fresh context window produces usable transcript companion logs; Haiku did not.

## Transcript backups: /log pre-gathers metadata only, subagent reads content

`/log` calls `list-transcripts-here.sh` to pull compact JSON metadata (backup names, session IDs, paths) — no transcript content. Full JSONL content is read only by the Sonnet subagent in its own context window via `extract-transcripts.py --extract`. Keeps the parent skill's context small while still giving the subagent everything it needs.

## Transcript backups: Tracking file is JSON at `~/.claude/transcript-backups/tracking.json`

Machine-readable JSON (not a markdown table) because both the pre-compact hook (bash) and the /log skill / subagent (python) need to update it. JSON parses trivially from both; markdown tables do not.

## Skill-helper scripts: Live in claude-foundations, symlinked to `~/.claude/scripts/`

`~/.claude/` always resolves to the default profile directory regardless of `CLAUDE_CONFIG_DIR`, making `~/.claude/scripts/` a stable location accessible from all profiles. Scripts live canonically in `claude-foundations/scripts/` and `install-hooks.sh` symlinks them in. Same pattern as hooks.

## install-hooks: Curated `SKILL_HELPERS` array, not blanket symlink

Not every script in `claude-foundations/scripts/` belongs in `~/.claude/scripts/` — only those referenced by skills. `install-hooks.sh` keeps an explicit `SKILL_HELPERS` array as the authoritative list of which scripts to symlink. Regular scripts (statusline.sh, set-topic.sh, etc.) are accessed via their full repo path.