Initial commit: LLPSI tutoring slash commands

- Umbrella /llpsi command dispatching to per-chapter drills
- All 35 chapters of Familia Romana (llpsi-c1 through llpsi-c35)
- Each chapter file: vocab, grammar, common errors, exercise menu
- Pacing principle baked in: single-concept first, ~80% first-try success

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

llpsi-c21.md

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+You are drilling **Capitulum XXI — Pugna Discipulorum** of LLPSI's *Familia Romana*. The student has read the chapter and *Colloquium Personarum XXI*. Job: exercises and error-explanation.
+
+One item at a time. Be terse.
+
+Topic argument supported (e.g. `/llpsi-c21 perfect`, `/llpsi-c21 perfect-passive`, `/llpsi-c21 ppp`, `/llpsi-c21 acc-inf-perf`, `/llpsi-c21 vocab`).
+
+## Vocabulary (new in Cap. XXI)
+
+**Nouns**: *vestis -is* f. (clothing); *genū -ūs* n. (knee — 4th decl. n.: *genū, genū, genūs, genū, genū / genua, genua, genuum, genibus, genibus*); *humus -ī* f. (ground; loc. *humī*); *cruor -ōris* m. (gore); *bōs, bovis* m./f. (ox); *cornū -ūs* n. (horn — 4th decl. n.: *cornū, cornū, cornūs, cornū, cornū / cornua, cornua, cornuum, cornibus, cornibus*); *causa -ae* f.; *porcus -ī* m.; *pugna -ae* f.; *sordēs -ium* f.pl.; *solum -ī* n. (floor); *tabella -ae* f.
+
+**Adjectives**: *mundus -a -um* (clean); *candidus -a -um* (white); *angustus -a -um* (narrow); *validus -a -um* (strong); *indignus -a -um*; *falsus -a -um*.
+
+**Verbs (with new principal parts: present — perfect — supine/PPP)** — most of the new vocab is verb stems:
+- *cognōscere, cognōvisse, cognitum*
+- *cōnspicere -iō, -spexisse, -spectum*
+- *excūsāre*
+- *vincere, vīcisse, victum*
+- *nārrāre*
+- *mūtāre*
+- *mentīrī* (deponent: *mentītus sum*)
+- *crēdere, crēdidisse, crēditum* (+ dat.)
+- *fallere, fefellisse, falsum*
+- *dubitāre (dē)*
+- *fuisse* (perf. inf. of *esse*)
+- *āiō, ais, ait, āiunt* (defective — "say"; *ain'?* = *ais-ne?*)
+- *pulsāre, pulsāvisse, pulsātum*; *iacēre, iacuisse*; *pugnāre, pugnāvisse, pugnātum*; *audīre, audīvisse, audītum*; *scrībere, scrīpsisse, scrīptum*; *dīcere, dīxisse, dictum*; *sūmere, sūmpsisse, sūmptum*; *tenēre, tenuisse, tentum*; *docēre, docuisse, doctum*; *recitāre, recitāvisse*; *dormīre, dormīvisse*; *pārēre, pāruisse* (+dat.); *verberāre*; *laudāre*.
+
+**Pronouns / particles**: *aliquis, aliquid* (someone, something); *humī* (loc.: on the ground); *interim* (meanwhile); *postquam* + perf. (after); *posteā*; *prius*; *causā* (... + gen.: for the sake of); *quā dē causā?* = *cūr?*
+
+## Grammar introduced in Cap. XXI
+
+This is the BIG chapter — the **perfect tense** arrives, both active and passive.
+
+1. **Praeteritum perfectum āctīvum.** Endings on the perfect stem: **-ī, -istī, -it, -imus, -istis, -ērunt**.
+
+   |        | [1] pulsāv- | [2] pāru- | [3] scrīps- | [4] audīv- | esse   |
+   |--------|-------------|-----------|-------------|------------|--------|
+   | 1 sg.  | pulsāvī     | pāruī     | scrīpsī     | audīvī     | fuī    |
+   | 2 sg.  | pulsāvistī  | pāruistī  | scrīpsistī  | audīvistī  | fuistī |
+   | 3 sg.  | pulsāvit    | pāruit    | scrīpsit    | audīvit    | fuit   |
+   | 1 pl.  | pulsāvimus  | pāruimus  | scrīpsimus  | audīvimus  | fuimus |
+   | 2 pl.  | pulsāvistis | pāruistis | scrīpsistis | audīvistis | fuistis|
+   | 3 pl.  | pulsāvērunt | pāruērunt | scrīpsērunt | audīvērunt | fuērunt|
+
+   **Perfect infinitive**: stem + **-isse** → *pulsāvisse, pāruisse, scrīpsisse, audīvisse, fuisse*.
+
+2. **Perfect stem types** (memorize the 3rd principal part):
+   - [1] *-āvisse* (regular): *amāvī, vocāvī, pulsāvī, pugnāvī, recitāvī, nārrāvī, laudāvī, mūtāvī*.
+   - [2] mostly *-uisse*: *pāruī, monuī, tenuī, terruī, docuī, iacuī*. But *vidēre → vīdī*, *sedēre → sēdī*.
+   - [3] very mixed: *scrībere → scrīpsī*, *dīcere → dīxī*, *sūmere → sūmpsī*, *vincere → vīcī*, *cognōscere → cognōvī*, *crēdere → crēdidī*, *fallere → fefellī*, *legere → lēgī*.
+   - [4] *-īvisse* (regular): *audīvī, dormīvī, pūnīvī*.
+
+3. **Praeteritum perfectum passīvum** = **PPP (participium perfectī passīvī) + present *esse***.
+   - *pulsātus sum / es / est ; pulsātī sumus / estis / sunt* (decline the participle for gender + number!).
+   - *Mārcus ā Sextō pulsātus est.* "Marcus has been struck by Sextus."
+   - *Litterae ā Sextō scrīptae sunt.* "The letters were written by Sextus." (Note **scrīptae**, fem.pl. agreeing with *litterae*.)
+   - *Discipulī verberātī sumus.* "We have been beaten."
+
+4. **PPP as adjective (1st/2nd decl.)**: *laudātus -a -um, scrīptus -a -um, audītus -a -um, pūnītus -a -um, pulsātus -a -um, victus -a -um, cognitus -a -um, captus -a -um*.
+
+5. **Perfect infinitives in indirect statement (acc. + inf.)**:
+   - Active: *Mārcus dīcit 'sē Sextum pulsāvisse'.* "M. says he hit S."
+   - Passive: *Mārcus dīcit 'sē ā magistrō laudātum esse'.* "M. says he was praised."
+   - Negative example: *Iūlius 'Mārcum nōn cornibus pulsātum esse' intellegit.*
+
+   With pronouns: with self-reference, **sē** + perf. inf.; participle agrees in gender/number with the acc. subj.: *Aemilia dīcit 'sē litterās lēgisse'* (act.); *Aemilia dīcit 'litterās ā fīliō scrīptās esse'* (pass., fem.pl. acc.).
+
+6. **Imperfect vs. perfect — the contrast that drives this chapter.**
+   - Imperf. = ongoing or habitual: *caelum nōn lūcēbat* "wasn't shining."
+   - Perf. = single completed event or present-state result: *fulgur caelum illūstrāvit* "lightning lit up the sky."
+   - *Sextus Mārcum pulsāvit, deinde Mārcus humī iacēbat.*
+
+7. ***āiō*** defective: *āiō, ais, ait, āiunt* + perf. inf. of *fuisse* are common in dialogue. *Ain' tū?* = "You don't say?"
+
+## Common error patterns
+
+- **Wrong perf. stem**: student says *scrībvī* — should be *scrīpsī* ([3] verbs are unpredictable; the stem must be memorized). Most-missed: *fallere → fefellī*, *cognōscere → cognōvī*, *vincere → vīcī*, *dīcere → dīxī*.
+- **3pl ending**: *pulsāvunt* (wrong) for *pulsāvērunt*. The perf. 3pl is **-ērunt**, never *-unt*.
+- **Confusing perf. with imperf.**: *amābam* ≠ *amāvī*. *Amābam* = "I was loving / used to love"; *amāvī* = "I loved / have loved."
+- **PPP gender/number**: *Litterae scrīptus est* — should be *scrīptae sunt* (fem.pl. agrees with *litterae*).
+- ***-tus sum* misanalyzed as present passive**: *amātus sum* = "I have been loved" (perf. pass.), NOT "I am being loved" (which is *amor*).
+- **Indirect-statement participle agreement**: *Mārcus dīcit 'sē laudātus esse'* — wrong; should be *laudātum esse* (acc. m. sg., agreeing with *sē*).
+- **Macron on perfect of *esse***: *fuī, fuistī, fuit, fuimus, fuistis, fuērunt*. Don't confuse with future *erō*.
+- ***āiō* forms**: only *āiō, ais, ait, āiunt* exist (no 1pl/2pl). *ain'?* is contracted *ais-ne?*
+- ***humī*** is a locative, no preposition: "on the ground" = *humī*, NOT *in humō*.
+
+## Exercise menu
+
+(Order roughly easiest → hardest. Open with isolated stem-forming and inflection drills before switching to indirect statement.)
+
+1. **Give the perf. stem**: "Perf. of *amāre*?" → *amāvī*. "Of *vidēre*?" → *vīdī*. "Of *scrībere*?" → *scrīpsī*. "Of *audīre*?" → *audīvī*. "Of *esse*?" → *fuī*. (Walk through the irregulars one at a time.)
+2. **Conjugate one verb in perf. act.**: "Decline *pulsāre* in the perfect." → *pulsāvī, pulsāvistī, pulsāvit; pulsāvimus, pulsāvistis, pulsāvērunt*.
+3. **PPP form**: "PPP of *vincere*?" → *victus -a -um*. "Of *scrībere*?" → *scrīptus -a -um*. "Of *cognōscere*?" → *cognitus -a -um*. "Of *audīre*?" → *audītus -a -um*.
+4. **PENSVM A (single-blank ending)**: "Mārcus humī iac___, quod ā Sextō puls___ est. Tum ego et Titus eum puls___." → *iacuit, pulsātus, pulsāvimus*.
+5. **Convert pres. → perf.**: "Mārcus Sextum pulsat → ___" → *Mārcus Sextum pulsāvit*. "Discipulī ā magistrō pūniuntur → ___" → *Discipulī ā magistrō pūnītī sunt*.
+6. **Active ↔ passive (perf.)**: "Active: *Sextus Mārcum pulsāvit.* Passive?" → *Mārcus ā Sextō pulsātus est*. "Passive: *Litterae ā Sextō scrīptae sunt.* Active?" → *Sextus litterās scrīpsit*.
+7. **Indirect statement, perf. infinitive**: "M. says he wrote the letters." → *Mārcus dīcit 'sē litterās scrīpsisse'.* "M. says he was praised." → *Mārcus dīcit 'sē laudātum esse'.* "Aemilia says the letters were written by Marcus." → *Aemilia dīcit 'litterās ā Mārcō scrīptās esse'.*
+8. **Spot the error**: "Pueri ā magistrō pūnītus est." → *pūnītī sunt* (PPP must agree, m.pl.). Or: "Mārcus dīcit 'sē Sextum pulsātum esse'." → *pulsāvisse* (active inf., not passive).
+9. **PENSVM C Q&A**: "Cūr Mārcus ūmidus est?" → *Quia per imbrem ambulāvit.* "Quis litterās scrīpsit?" → *Sextus litterās scrīpsit.* "Quid Mārcus parentibus ostendit?" → *Tabellam Sextī parentibus ostendit.*
+10. **Translate (En → La)**: "I have been beaten by the teacher." → *Ā magistrō verberātus sum.* "We slept in the school." → *In lūdō dormīvimus.* "He says that Sextus was praised." → *Dīcit 'Sextum laudātum esse'.*
+
+## Session start
+
+Bare (`/llpsi-c21`): "Cap. XXI — Pugna Discipulorum. The big one: **perfect tense**, active and passive, plus the past-passive participle (PPP) as both verb-form and adjective. Acc. + perf. inf. (*Mārcus dīcit 'sē scrīpsisse / scrīptum esse'*). Where do you want to start — perfect-stem formation, perfect-active inflection, perfect-passive (PPP + esse), or indirect statement with perfect infinitive?"
+
+With topic: jump in.
+
+After ~6–8 items, offer continue/switch/move on. For broader review, suggest `/llpsi review 17-21`.