Historian Plugin

Session memory. Checks past sessions before redundant research, planning, or debugging.

Hooks

Hook	When	Action
PreToolUse(WebSearch/WebFetch)	Before web research	Checks find_similar_queries() first
PreToolUse(EnterPlanMode)	Before planning	Searches search_plans() for past approaches
PreToolUse(Task)	Before agents	Checks find_tool_patterns() for workflows
PostToolUse(Bash)	After errors	Suggests get_error_solutions()

Commands

Command	Description
/search-historian <query>	Search past sessions for solutions, decisions, context

Workflows

Search (standalone)

1. search_conversations("query") — full-text across all sessions
2. If error-related: get_error_solutions("error pattern")
3. If file-related: find_file_context("filename")
4. Summarize relevant findings

Search (with siblings)

1. search_conversations("query") — historian's own search
2. If praetorian active: praetorian_restore("query") for compacted context (denser than raw history)
3. If oracle active: search("query") when error patterns suggest a missing tool
4. Combine: historian provides breadth (all sessions), praetorian provides depth (curated insights)

Error Resolution (standalone)

1. get_error_solutions("error pattern") — how was this fixed before?
2. If found: apply the previous solution
3. If not: proceed with normal debugging

Error Resolution (with siblings)

1. get_error_solutions("error pattern") — historian checks past fixes
2. If oracle active: search("error tool") for tools that address this error class
3. If gladiator active: check if this error was already observed as a pattern
4. Present combined findings: past fix + available tools + pattern context

Sibling Synergy

Sibling	Value	How
Praetorian	Research will be compacted after	Praetorian prompts saving after web searches historian triggers
Oracle	Tools found for error patterns	Oracle searches for tools when historian finds recurring errors
Gladiator	Observations correlate with history	Past solutions enrich gladiator reflection
Vigil	Checkpoints complement history	File state preserved alongside session history

MCP Tools Reference

Tool	Purpose
search_conversations	General history search
find_similar_queries	Find related past questions
get_error_solutions	Find how errors were fixed
find_file_context	Track file changes
find_tool_patterns	Discover successful workflows
list_recent_sessions	Browse recent work
search_plans	Find past implementation plans

Requires

claude mcp add historian -- npx claude-historian-mcp