feat(plugin): add proactive ctx_memory save guidance to agent prompts

Agents now get concrete examples of when to write project memories:
after spending multiple turns finding a path, discovering a non-obvious
command, or learning a constraint the hard way. This reduces repetitive
searches across sessions.

Author: ualtinok

packages/plugin/src/agents/magic-context-prompt.ts

@@ -20,6 +20,10 @@ Use \`ctx_reduce\` to manage context size. It supports one operation:
 Syntax: "3-5", "1,2,9", or "1-5,8,12-15". Last ${protectedTags} tags are protected.
 Use \`ctx_note\` for deferred intentions — things to tackle later, not right now. NOT for task tracking (use todos). Notes survive context compression and you'll be reminded at natural work boundaries (after commits, historian runs, todo completion).
 Use \`ctx_memory\` to manage cross-session project memories. Write new memories or delete stale ones. Memories persist across sessions and are automatically injected into new sessions.
+**Save to memory proactively**: If you spent multiple turns finding something (a file path, a DB location, a config pattern, a workaround), save it with \`ctx_memory\` so future sessions don't repeat the search. Examples:
+- Found a project's source code path after searching → \`ctx_memory(action="write", category="ENVIRONMENT", content="OpenCode source is at ~/Work/OSS/opencode")\`
+- Discovered a non-obvious build/test command → \`ctx_memory(action="write", category="WORKFLOW_RULES", content="Always use scripts/release.sh for releases")\`
+- Learned a constraint the hard way → \`ctx_memory(action="write", category="CONSTRAINTS", content="Dashboard Tauri build needs RGBA PNGs, not grayscale")\`
 Use \`ctx_search\` to search across project memories, session facts, and conversation history from one query.
 Use \`ctx_expand\` to decompress a compartment range to see the original conversation transcript. Use \`start\`/\`end\` from \`<compartment start=N end=M>\` attributes. Returns the compacted U:/A: transcript for that message range, capped at ~15K tokens.
 **Search before asking the user**: If you can't remember or don't know something that might have been discussed before or stored in project memory, use \`ctx_search\` before asking the user. Examples:
@@ -38,6 +42,10 @@ Before your turn finishes, consider using \`ctx_reduce\` to drop large tool outp
 const BASE_INTRO_NO_REDUCE = `Messages and tool outputs are tagged with §N§ identifiers (e.g., §1§, §42§).
 Use \`ctx_note\` for deferred intentions — things to tackle later, not right now. NOT for task tracking (use todos). Notes survive context compression and you'll be reminded at natural work boundaries (after commits, historian runs, todo completion).
 Use \`ctx_memory\` to manage cross-session project memories. Write new memories or delete stale ones. Memories persist across sessions and are automatically injected into new sessions.
+**Save to memory proactively**: If you spent multiple turns finding something (a file path, a DB location, a config pattern, a workaround), save it with \`ctx_memory\` so future sessions don't repeat the search. Examples:
+- Found a project's source code path after searching → \`ctx_memory(action="write", category="ENVIRONMENT", content="OpenCode source is at ~/Work/OSS/opencode")\`
+- Discovered a non-obvious build/test command → \`ctx_memory(action="write", category="WORKFLOW_RULES", content="Always use scripts/release.sh for releases")\`
+- Learned a constraint the hard way → \`ctx_memory(action="write", category="CONSTRAINTS", content="Dashboard Tauri build needs RGBA PNGs, not grayscale")\`
 Use \`ctx_search\` to search across project memories, session facts, and conversation history from one query.
 Use \`ctx_expand\` to decompress a compartment range to see the original conversation transcript. Use \`start\`/\`end\` from \`<compartment start=N end=M>\` attributes. Returns the compacted U:/A: transcript for that message range, capped at ~15K tokens.
 **Search before asking the user**: If you can't remember or don't know something that might have been discussed before or stored in project memory, use \`ctx_search\` before asking the user. Examples: